Welcome to the Mandatory Monday Ranking Files, a six-part series rating the best and worst units in the NFL. In this week's kickoff segment, we battle through the offensive lines.

If you are looking for safe, conventional selections, look elsewhere! The Mandatory Monday team (just me, actually) assembled the best analytic tools available for dissecting offensive line performance, made adjustments to account for a busy offseason and the development of prospects, and added heavy doses of scouting knowledge and horse sense. As a result, these are the best and worst offensive lines based on anticipated 2014 performance, not reputation.

Before we get to the rankings, a little housekeeping. Throughout this series, we will rank the Top Five, Bottom Five and a handful of teams in the middle Worth Mentioning. Why not all 32 teams? First, that takes a long time, and it is better to spend three paragraphs talking about a great line than to conserve energy for a few sentences about the 19th-best line. Second, the difference between the seventh and 17th-best offensive line (or any other unit) often amounts to little on the field and can be impossible to quantify in the offseason, but it can make for fightin' words in an article. Yes, dear editors, fightin' words lead to more page views, but these ratings will provide plenty of grist without being argumentative for their own sake.

Offensive lines are evaluated with a big boost from Football Outsiders' Adjusted Line Yards and Adjusted Sack Rate metrics. Both of these stats filter out lots of biases, like schedule strength (a big deal when evaluating NFC West teams) and outlier statistics that make a line look better or worse than it really is (like a pair of 80-yard runs that juice rushing totals, or a low sack total caused by a team that rarely has to throw). Other FO stats are sprinkled into the rankings, including Blown Blocks tabulated from game-by-game scouting. Major free-agent signings and departures, new draftees and 2013 rookies on the line also factor heavily into the calculations, as does the stability of the coaching staff: If a system has been in place for several years, the "ordinary" veteran starters in that system earn a little boost.

Finally, there is some dead reckoning. We all know some quarterbacks can make their offensive lines look great. Some schemes are more conducive to low or high sack totals than others. It's impossible to filter these forces out completely. But we can acknowledge them, study them, make the best possible judgments and reach a conclusion that, while a little controversial, makes a lot of sense when you push past your prejudices.

The Five Best Offensive Lines

1. Dallas Cowboys. Cowboys bashers can scoff if they like, but the team has a tremendous line. It all starts with Tyron Smith, one of the best offensive linemen in the NFL right now. Smith allowed just three sacks last year and is the best run-blocking left tackle in the league. Right tackle Doug Free is a solid run blocker who rarely makes mistakes in pass protection and has not missed a start in four years.

Smith is outstanding and Free is good, but the prospects are what bring this line to the next level. Travis Frederick had a fine rookie campaign and will start at center for the rest of the decade. Rookie Zack Martin moves over from collegiate tackle to give the Cowboys a massive, athletic, nearly game-ready guard to fill the line's biggest hole from last year. Martin is already counterproductively clobbering Cowboys defenders in minicamp, but gains on the offensive line always come at the expense of the defense in Dallas for some reason (see Frederick's early selection at the expense of a much-needed defender in the 2013 draft). That's a problem for a later series of articles.

As for the Cowboys bashers, bear with me … if Jason Garrett is a ninny and Tony Romo is a chokity-choke and Dez Bryant is a headcase and the running backs are all Lance Dunbar types that Jerry Jones fell in love with while eating caviar and barbecue in front of the 230-inch television on a Saturday afternoon, then how do the Cowboys average nearly 28 points per game? Somebody besides Jason Witten is doing something right. Five somebodies, to be precise.

2. New England Patriots. Often overlooked as just a beefy extension of Tom Brady's will and the Patriots Way, sometimes maligned by excellence-gorged Patriots fans who believe an electrified barbed-wire fence should be erected around His Infallibleship, the Patriots line quietly makes perennial 12-win seasons possible for a team that treats running backs like single-serving coffee pods.

At first glance, last year's Patriots line performance does not look that great. Brady was sacked more than in any season since 2001, and both center Ryan Wendell and left tackle Nate Solder made more than their shares of mistakes in pass protection. Take a deeper look, however, and you see that the Patriots interchanged four running backs but still rushed for over 2,000 yards, and that life in the Patriots passing game was harder than it has been in over a decade because of injuries and defections among the receivers. In a season of change, the line was a stabilizing factor.

Speaking of stability, Logan Mankins made his sixth Pro Bowl last year, while Dan Connolly enters his fifth season as a Patriots starter in the interior. Solder had some rough midseason games (Bengals and Jets, particularly) and suffered an end-of-year concussion, but he can be outstanding for long stretches, and Sebastian Vollmer is one of the best right tackles in the NFL when healthy. Wendell, the weakest link on the line, must find a better way to cope with Mo Wilkerson and Sheldon Richardson twice per year or he will face swift, stiff competition: Rookie Bryan Stork has the brains and toughness to make a quick move up the depth chart.

Depth is the Patriots line's secret weapon. Stork is a well-regarded prospect. Marcus Cannon is a massive super-sub who played well in place of Vollmer and others last year. Guard Josh Kline played mistake-free and opened some holes in a spot start last year, and rookies Cameron Fleming and Jon Halapio ensure depth-chart competition. Some teams may boast a more talented top five, but none can offer a more prepared and capable top eight.  

3. New Orleans Saints. The Saints do not have an experienced center. That is a real problem, and it is the one thing keeping them from the top of this list, because everything else about their offensive line is aces.

Ben Grubbs and Jahri Evans are a pair of Pro Bowl guards in a system that requires guards to pull and molly-block in pass protection more than other teams. Right tackle Zach Strief has been in the system for eight years, reliably starting for the last three. Terron Armstead's "rookie lumps" consisted of one start against the Panthers. He allowed two sacks and false started twice, then settled down and played nearly mistake-free football through the playoffs. He is a top-talent prospect on the Sean Payton fast track.

Payton and Drew Brees can make pass protectors look better, but it's telling that Payton can plug Khiry Robinson types in behind this line and still get solid rushing performances. If only center Tim Lelito inspired more confidence. He allowed four sacks in a pair of starts at guard, and there is buzz that the Saints may sign 35-year old Jonathan Goodwin, the team's starter during the 2009 Super Bowl run, as insurance. Whoever starts at center gets to play between Grubbs, Evans and Brees; no one could ask for a better support network.

4. Detroit Lions. A not-so-surprising surprise entry on the list. The Lions allowed just 23 sacks last season; only the Broncos allowed fewer, and everyone knows Peyton Manning's pre-snap prairie geography lessons are much of the reason. The Lions line got a similar boost from a passing game built around sudden snap-throw plays, but that does not explain the team's prowess in short-yardage situations. The Lions finished third in Football Outsiders' Power Success metric, converting 76 percent of their third- or fourth-and-short or goal-to-go rushing attempts. This is a team that uses Reggie Bush as a featured runner, for heaven's sake!

OK, so bowling ball Joique Bell replaces Bush when it is time for the one-yard plunge; Bell is rugged, but he ain't Marshawn Lynch. The star of the Lions line is second-year guard Larry Warford. If it is possible for you to get excited about a young guard, then Warford excites you: He is already an error-free pass protector and effective run blocker. LaAdrian Waddle took over at right tackle during an injury crunch last year and would have earned Undrafted Rookie of the Year honors if there were such a thing. (Say, that's a swell idea; someone tweet at me in December and remind me to write an article giving an "award" to the best undrafted rookie of the year.) Dominic Raiola is nearing the end of the line -- 14 seasons in Detroit count 28,000 years against a sentence in purgatory -- but he is coming off another rock-solid season, and rookie Travis Swanson assures an orderly succession.

The left side of the Lions line is not as young or impressive, but Riley Reiff rebounded from a messy rookie year last season despite numerous aches and pains, and Rob Sims is durable and capable. New coach Jim Caldwell has brought out both the best (the Peyton Manning lines) and worst (last year's Ravens) in pass protection over the years, but given outstanding raw material and veterans who are already used to a three-wide, quick-passing base offense, he could make a very good line even better.

5. San Diego Chargers. Nick Hardwick has been around so long that he has workout shorts labeled "Los Angeles Chargers." Hardwick made the Pro Bowl in 2006, two coaching regimes ago, then the world forgot about him as the Chargers laid down dusty layers of awesome, awful and indifferent over the fossils of the Schottenheimer era. Hardwick snapped the football to his quarterback 1,075 times last year and allowed zero sacks while blowing just four total blocks. So it is time to do a little paleontology and unearth Hardwick's reputation.

King Dunlap is … good? I am sorry, but I spent many summer afternoons in Eagles camp, and it always looked like Andy Reid had erected a cell-phone tower on the line of scrimmage and slapped a No. 65 jersey on it. But yes, Dunlap was very good in 2013, as was free-agent pickup Chad Reinhart at guard. The Chargers allowed just 20 sacks as the result of blown blocks (as opposed to obvious coverage sacks or untouched blitzers), one of the lowest totals in the NFL, and anyone who watched them late in the season knows that their running game suddenly blossomed after years of wishful Ryan Mathews thinking. Mathews and the other runners were stuffed for no gain or a loss on just 12 percent of carries, the lowest rate in the NFL in 2013.

Our line rating system gives the Chargers a boost for second-year starter D.J. Fluker, even though Fluker is basically one of those slow-moving walls that video game characters easily dodge at this point in his career. On some plays, it looked like Philip Rivers just assumed that the defender would beat Fluker and avoided sacks by preplanning an escape. Fluker has potential to improve, and when he gets his paws on you, you are going backward. Jeromey Clary also had his troubles, and the Chargers drafted Notre Dame's Chris Watt as a contingency plan. But one thing you learn when analyzing modern offensive lines is that there are no Hogs or 1992 Cowboys right now. There are only lines with solid talent at several positions and schemes that put everyone in the best positions. The Chargers have both of those things.

Worth Mentioning

Pro Bowl left tackle Ryan Clady will return to the Broncos after missing much of the 2013 season. (USA TODAY Sports)

Top 10: Denver Broncos. Anytime you rate a Peyton Manning offensive line, you must remember that it is a Peyton Manning offensive line. No quarterback in NFL history, not even Dan Marino, has done more to make his lines look better, from solving problems with pre-snap audibles to releasing the ball quickly to using the space within the pocket the way Rembrandt used a canvas.

So the Broncos line looks great on the stat spreadsheets, and Ryan Clady's return from a foot injury gives them a Pro Bowl boost at the most important position. But reasons for skepticism knock the Broncos out of the top five: They lost Zane Beadles, and they are sliding several linemen into new positions to accommodate Clady's return and Beadles' departure. Plus, memories of the Super Bowl are still pretty fresh. The personnel is solid enough, but if the Broncos ever need their line to elevate Peyton Manning -- as opposed to vice versa -- they may be in for another rude shock like the one they felt in February.

Top 10: San Francisco 49ers. The Niners have two Pro Bowlers on their offensive line, have enjoyed stability along the line for years, and of course are in the NFC title game every year. So conventional wisdom should put their offensive line in the top five. There's only one problem: The 49ers line often looks terrible according to statistical analysis. The team's sack rate is high -- 39 sacks are a lot for a team that runs the ball constantly -- and the yards per carry are low when you filter out Colin Kaepernick's scrambles and options.

A little investigation reveals that 14 of the Niners sacks allowed last year were either coverage sacks or scrambles gone wrong. Blame the receivers for not getting open or Kaepernick for not seeing them if you like, but don't blame the linemen. As for the relatively low per-carry production, there are many extenuating circumstances, from constant NFC West battles to the number of times Frank Gore and Kendall Hunter plunge off tackle to protect fourth-quarter leads.

Few offensive lines are asked to do more in the running game than the 49ers, who are constantly pulling, trapping and crisscrossing to power an intricate ground attack. So the 49ers definitely have the NFL's most unique offensive line. And there are plenty of reasons to include it in the top 10. But all of the punting and sputtering the 49ers do while their defense keeps opponents pinned to the turf provides enough skepticism to keep their line out of the top five.

On the Rise: Chicago Bears. No offensive line in the NFL improved more than the Bears line last season, and the emergences of two rookie starters (including Pro Bowl selection Kyle Long) pushed the Bears into the top 10, according to our system. The Bears were a pretty terrible short-yardage team, though backup running back Michael Bush was a big part of the problem, and left tackle Jermon Bushrod only looks like a great player after three years of gaping at J'Marcus the Cutler Killer Webb. But they can shoot up this list if Long and right tackle Jordan Mills keep developing and the transition from Roberto Garza to Brian De La Puente at center goes smoothly.

On the Rise: Tennessee Titans. No team in the NFL has an offensive line as far superior to the rest of the units on their team as the Titans. The rating system grades the Titans as a middle-of-the-pack line, but a spreadsheet can only do so much with such a unique set of circumstances. The Titans had an awful quarterback situation in 2013, and it won't be much better in 2014. Chris Johnson could take an afternoon's worth of five-yard holes and turn them into 19 one-yard plunges and one long touchdown, frazzling any effort to objectively analyze his blockers. And two-thirds of the Titans line talent falls into the "prospect" category: center Brian Schwenke, guard Chance Warmack and rookie Taylor Lewan.

Veterans Michael Roos and Andy Levitre anchor the left side, Schwenke and Warmack had encouraging rookie seasons and Michael Oher is on hand to battle Lewan at right tackle. Veteran super-sub in the middle Chris Spencer provides even more depth. Unfortunately, the backfield still consists of Jake Locker and rookies. If Locker suddenly looks great or Shonn Greene joins Bishop Sankey to rush for 2,000 yards, the only logical end-of-year conclusion will be that the Titans had the NFL's best offensive line in 2014.

From the Ashes: Miami Dolphins. A busy offseason kept the Dolphins out of the bottom five. Based on last year's results alone, they were the far worst offensive line on the list, but you probably knew that. Dolphins linemen blew 43 blocks that led to sacks last season; no other team suffered more than 34. Branden Albert and Ja'Wuan James don't make the Dolphins great, but they should be light years above terrible.

The Five Worst Offensive Lines

The Steelers offensive line desperately needs improvement from guard David DeCastro, among others. (USA TODAY Sports)

28. Pittsburgh Steelers. Maurkice Pouncey is back. Mike Munchak is the latest line-coach cook to try to stir the blocking broth, and he is a good one. Le'Veon Bell gives the Steelers a power runner who can make the most of what an offensive line offers him. The Steelers line looked much better in the second half of last season than the first half, so everything is fine, right?

Not quite. David DeCastro's development at guard has been slower than expected. Mike Adams has been developing in reverse. Marcus Gilbert, drafted as a left tackle, has become an injury- and penalty-prone (though not terrible) right tackle. Kelvin Beachum is now the left tackle, and while the former seventh-round pick is capable enough, he doesn't make anyone forget that he won his job because two bigger-reputation prospects lost theirs.

The Steelers offensive line finished near the middle of the analytical pack in 2013 due to second-half improvement, but the team needed a talent upgrade that the draft did not provide until the fifth round. Maybe Munchak is the missing puzzle piece: There is still time for a great coach to get the most out of DeCastro, Gilbert and Adams. Didn't we say the same thing last year about Jack Bicknell?

29. Buffalo Bills. Evaluating an offensive line playing in front of novice quarterbacks can be tricky. EJ Manuel took 28 sacks last year, but he was a rookie who barely played in training camp. Thad Lewis endured 18 sacks in just 157 pass attempts, but Lewis was an off-the-wire emergency replacement. Football Outsiders considers 17 of the sacks allowed by the Bills to be "coverage sacks," the most in the NFL. A few of those receivers were probably not as covered as inexperienced Manuel, Lewis and Jeff Tuel thought they were?

So why not take the Bills off the hook? Cordy Glenn, after all, is growing into one of the league's best tackles, a snarling hulk of a man who resembles Tyron Smith in many ways. But there are plenty of issues to Glenn's right. Center Eric Wood committed seven holds and 10 total penalties last season. Right tackle Chris Hairston has been suffering from a complex menu of foot and ankle injuries since 2012, so the team is likely to rely upon Erik Pears (adequate) and rookie Chris Kouandjio (another medical mystery case) unless Hairston can stop his slide into vaporware.

And then there is Chris Williams, the Ted McGinley of offensive linemen. The Bears, at their wishful-thinking worst, slid Williams from top left tackle prospect to right tackle to guard to backup center to Mike Tice golf caddie. The Rams then acquired Williams to ensure that Sam Bradford did not get any funny ideas about getting comfortable in the pocket. If you are planning to start Chris Williams, you need to do some better planning. The Bills have rookie Cyril Richardson in the fold, but the name "Chris Williams" atop a depth chart is reason enough to keep an offensive line near the bottom of any list.

30. Seattle Seahawks. The Seahawks will be camping in the top five for most of this series; don't expect a lot of drama when the secondary rankings come out in two weeks. But they have come by this lone appearance at the bottom honestly.

Don't believe it? Explain how a team with Marshawn Lynch and an option threat at quarterback finished dead last in the league in converting power situations: The Seahawks got the job done on just 49 percent of short-yardage and goal-to-go conversions. Explain how Russell Wilson got sacked 44 times, despite the fact that the Seahawks rarely faced the kind of pressure-passing situations that lead to easy sacks. Finally, take a look at the three-fifths of their line that are not named Max Unger or Russell Okung, and note that two regulars from last season are gone.

Yes, injuries to Unger and Okung played a role last season. Yes, one of Wilson's few flaws is his tendency to run backward into sacks at the worst possible times (on the verge of field-goal range, especially). Until Michael Bowie, rookie Justin Britt and others take the number of leaks down from three to zero or one, the Seahawks line is their designated Achilles' heel.

31. Jacksonville Jaguars. Unlike the Seahawks, the Jaguars aren't just hipster slumming in the bottom five for a week; they live in this non-gentrified neighborhood. The rating system gives Luke Joeckel credit for expected improvement in 2014, and Zane Beadles tosses some loose change in their tin cup, but that's about it. The Jaguars are breaking in a young, unknown center, and someone named Austin Pasztor is atop their depth chart at right tackle. It is rare for me to see the name of a projected NFL starter and draw a complete blank, so congratulations Austin Pasztor!

The Jaguars averaged 3.3 yards per rush and allowed 50 sacks last year, so witnesses for their defense cannot turn to much statistical evidence. Terrible skill-position players hurt those figures, but the Jaguars enter 2014 with longtime Vikings backup Toby Gerhart at running back and Chad Henne babysitting rookie Blake Bortles at quarterback -- not exactly Peyton Manning and Edgerrin James when it comes to forgiving the sins of a bad line, in other words. Then again, with a Pasztor at right tackle, maybe the Jaguars line can do its own forgiving.

32. Baltimore Ravens. The logic for Ravens line optimism in 2014 works something like this: 1) Eugene Monroe was better than Bryant "distracted by shiny and bacon-covered objects" McKinnie, so therefore Monroe is great; 2) Ricky Wagner looked terrible the last time he tried to play tackle for more than a few snaps, but Ravens youngsters always look terrible until they suddenly look good; 3) Gary Kubiak always builds great lines, so a wave of the zone-blocking magic wand can make everything better (as Texans fans saw in 2013); and 4) Jeremy Zuttah? Jeremy Zuttah!

And now for some pessimism. Ravens running backs averaged 3.1 yards per carry last year. Rushers were stuffed for no gain or a loss on 26 percent of carries, the worst rate in the NFL last year. The Ravens also allowed 48 sacks, though in-depth analysis reveals that the run blocking was heavily exacerbating the pass protection issues: when it is always third-and-long, sack totals naturally increase. And of course, personnel changes were minimal.

Zone blocking can work wonders for run blocking, which can make the pass protection look better, and Kubiak is steeped in the scheme. Zuttah may help, Monroe really did come on strong in the second half and the Ravens developmental pipeline has a fine track record. But that is a lot of finger-crossing and first aid over an awfully big wound.

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Housecleaning Items

The tentative schedule for the Mandatory Monday Ranking File: defensive front sevens on June 9, secondaries on June 16, skill positions on June 23, special teams on June 30 and quarterbacks on July 7 for the ultimate back-from-vacation treat. Everything is subject to change on a whim.

Check back all week as the Sports on Earth NFL team begins OTAs (Offseason Talk & Analysis), a team-by-team look at how the transaction season went and what's left for each team as they approach training camp. The Atlanta Falcons kick things off today!

Finally, I am proud to announce and shameless plug the arrival of my new book: A Good Walkthrough Spoiled: the Best of Mike Tanier at Football Outsiders. It's an alternate history of the NFL at the dawn of the social-networking era, a 400-page rant about Donovan McNabb, Chad Ochocinco and Tim Tebow. Relive the biggest events of NFL history from 2005-2012 through parodies of Alan Moore, C.S. Lewis and Eminem. Available in print and on gadgets! Makes a great dads and grads gift!