When a running game fails as totally as the Steelers running game failed last year, both the team and its fans search for answers in the offseason. Maybe it was the running backs. Maybe it was the offensive line. Maybe it was the coaches. Maybe it was the scheme.

For the Steelers, it was a little bit of everything, and their running game was one of the biggest reasons they failed to make the playoffs.

The Steelers have changed running backs. They have traded out some offensive linemen. They are changing their scheme, with the help of a new offensive line coach. It's as close to a total overhaul as you will ever see from the Steelers, the NFL's most patient, deliberate perennial contender.

The changes will make the Steelers running game better this year, because it would be hard for it to get worse. But the Steelers need more than a modest improvement. Good may not be good enough in the AFC North. For the Steelers to keep up with the Ravens and Bengals, a lot of little changes will have to make a huge difference.

The Running Backs

A scorecard of the comings and goings in the Steelers backfield:

Gone: Rashard Mendenhall. Mendenhall rushed back from a 2011 ACL injury last season, and he spent the season sluggish, nursing injuries, disgruntled, fumbling and sometimes benched. It was a lost year for the two-time 1,000 yard rusher, who is now with the Arizona Cardinals.

Here: Le'Veon Bell. Bell rushed for 1,793 yards for Michigan State last year. He also caught 32 passes, and offensive coordinator Todd Haley raved about Bell as a "three-down back" and a "workhorse" in minicamp. Bell is a big 230-pounder with light feet. He can cut and spin, and he has pretty good vision when reading blocks and deciding where to go. That ability to set up blocks is a must for a back in a zone-blocking scheme. More on that later.

Back: Jonathan Dwyer. Dwyer was the Steelers' leading rusher, and he was effective in spurts last year. He produced back-to-back 100-yard games against the Bengals and Redskins in Weeks 7 and 8, then missed a game with a quad injury. He was not as effective upon his return, and coaches were frustrated by his tendency to wear down after multiple carries. The Steelers shuffled him from workhorse to third-down back to committee back and back again in their quest for a viable rotation. Dwyer signed a one-year contract in the offseason and took minicamp reps with the first team, but everyone expects Bell to beat him for the starting job.

Gone: Chris Rainey. Talented but troubled, Rainey served as a return man and third-down back last year, his role waxing and waning based on the availability of other backs and the Steelers' confidence in him. Rainey was fumble-prone as a receiver and not quite as elusive as advertised. Two disturbing legal incidents in rapid succession ended his Steelers career in January.

Here: LaRod Stephens-Howling. Tough, tiny and dependable, Stephens-Howling lacks Rainey's potential but is a much more valuable bench piece. He has lost some of the explosive return ability he had in 2009 and 2010, but he handles special teams duties capably, won't kill you as a third-down back, and proved he was a decent pinch starter with two 100-yard games for the Cardinals last season. If Stephens-Howling is getting 20 offensive touches per game, the Steelers are in big trouble, but he can solve several problems as an all-purpose utility reserve.

Back: Isaac Redman. Redman rushed 26 times for 147 yards against the Giants in Week 9, the best performance by a Steelers running back all season. He then fumbled deep in Steelers territory early in the game against the Chiefs, fumbled again in the legendary Browns Butterfingers Bowl, and spent the rest of the season in the doghouse, bubbling up occasionally when Mendenhall, Dwyer or Rainey got into deeper doo-doo and the Steelers needed a body. Redman flashes Marshawn Lynch-style tackle-breaking ability and catches the ball well enough to be useful on third downs, but ball security is a major problem for him, and Bell now has many of the same skills.

Back: Baron Batch. The great-grandson of Charlie Batch, inheritor of a barony that prevents the Steelers from ever cutting him. Actually, a third-stringer who averaged 2.0 yards per carry last year but kept getting opportunities. Currently fifth on the depth chart, and unlikely to move up unless there are multiple injuries.

Verdict: The rebuilt backfield is deep and versatile, with a fine mix of talent, potential, and experience. Bell is a solid prospect; all three of the veterans behind him had occasional success last year and do a variety of things well. Everyone is healthy. Unless there is an ACL epidemic, these guys should move the ball, assuming that the Steelers' other changes prove successful.

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Unfortunately for Rashard Mendenhall and the Steelers, this was a frequent occurrence last year. (Getty Images)

The Scheme

The Steelers were the second worst team in the NFL at running up the middle, according to Football Outsiders. They averaged just 3.44 yards per rush, well below the league average of 4.05. Only the Cardinals were worse, and the Cardinals' running game was hampered by their passing game. (Note: Football Outsiders line stats are prorated so that one or two long runs in any direction do not skew the results.)

The Steelers ran up the middle far, far more than any other team in the NFL. A whopping 75 percent of their runs went between the guards. The NFL average is 52 percent. Only seven percent of Steelers runs went to the outside. The NFL average is 21 percent.

If insanity is doing the same thing over and over again and expecting different results, then the Steelers' running game was truly insane. The Steelers' running game was predicated on doing the thing they were worst at as frequently as possible.

New offensive line coach Jack Bicknell Jr. is determined to make the Steelers' running game boldly go where it rarely went in 2012: to the outside, and more than four yards downfield. He began installing some outside zone blocking plays in minicamp, and early reviews have been glowing. "It's a great new dynamic for us," guard Ramon Foster said. "I like it a lot," added tackle Marcus Gilbert. "It is going to help our offensive line a lot because guys are going to be on the move where they can take their guy and keep him moving, and we can cut back off of it," said Redman.

Or ask Maurkice Pouncey, the leader of the line: "We're still going to do a little of the power stuff, but I think outside zone now in the NFL is what's really working and getting guys running on the move and cutting them down is kind of the easiest thing to do right now," he said on ESPN Radio last week.

The Steelers did not use outside zone principles last year. They used some inside zone (similar, but with double teams in the middle instead of the edge), but they relied mostly on straight-ahead drive blocks and various pulling lineman plays. Sometimes, they used the same plays over and over, even when they were not working.

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Figure 1

Figure 1 shows a play they used several times against the Titans: a counter designed to get a hole for Mendenhall (34) off tackle. Two blockers pull on the play, including guard Ramon Foster (73), while left tackle Max Starks (78) ignores the defender on his outside shoulder and climbs to the linebacker level. The idea is that Foster or the pulling H-back will pin Starks' defender to the outside to create a cutback lane. Except … the defender stands both Foster and the H-back up, and Starks misses the first linebacker flowing toward the play! Mendenhall has nowhere to go and dives forward for that staple of the Steelers' running game, a gain of two.

The worst part of the play shown in Figure 1 is that the Steelers kept using it, as well as a similar inside run that Figure 1 was supposed to be the "counter" version of. The Titans were never fooled, nor were other opponents.

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Figure 2

Figure 2 shows an example of how an outside zone running play is blocked. There are two sets of "tandem" blocks shown in dark lines on the diagram. These are double teams, but either blocker can peel off the double team to take on a defender entering his gap, or ideally, to go on a search-and-destroy mission on the linebacker level. The running back (now wearing Bell's No. 26) often finds that the defensive line is a victim of its own momentum: Defenders beat their blockers to the outside, only to find those blockers nudging them further outside, creating wide gaps to the inside. The back is trained to read specific blocks to determine what is going on, and can bounce to the inside if the defense has been stretched thin. Outside zone plays do not necessarily produce outside runs -- they very often do not -- but they regularly provide rushing lanes to the inside, and the Steelers will take what they can get. 

The defense is using a very vanilla front in Figure 2; different defensive fronts call for different blocking patterns, as they do with any blocking scheme. Truly outstanding zone-blocking teams like the Texans and Redskins use inside and outside zone almost exclusively in the running game. The techniques are easy to learn but tough to master, and the team that dabbles often winds up with linemen who aren't clear on their ever-changing roles and running backs who never get the knack for reading and reacting while running sideways. Quickness is more important than raw power in zone blocking, and after watching Foster and Starks flail on their on-the-move blocks in Figure 1, it's clear that Bicknell has his hands full.

Most of the rumblings out of Pittsburgh suggest that zone blocking will get the emphasis it needs, both in training camp and in game plans. The Steelers have also made some changes up front. A younger, quicker line could make the outside zone scheme work, with a heavy emphasis on "could."

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Center Maurkice Pouncey (53) is the clear anchor of the Steelers' offensive line. (USA TODAY Sports)

The Line

A breakdown of the offensive linemen who are expected to master the new scheme with the help of the new coach and block for the new backfield. None of them are really new faces, but many have new roles:

Maurkice Pouncey, Center: The best player and unquestioned leader on the line. Pouncey got injured early in that Week 6 loss to the Titans, and it showed: The Steelers rushed for just 42 yards on 21 carries, once a Ben Roethlisberger sack is removed from the data. Pouncey is one of the best centers in the NFL and can adapt to any system.

David DeCastro, right guard: The Steelers' first-round pick last year, DeCastro dislocated a kneecap during a preseason game, erasing most of his season. He returned in time to have a pair of miserable games against the Cowboys and Bengals late in the year, with Marcus Spears and (especially) Geno Atkins abusing him. DeCastro is an excellent prospect, and while he appears to be built for a drive-blocking system, he has the athleticism and fundamentals to move laterally and zone block. He is a reason for optimism, but he is no sure thing.

Ramon Foster, left guard: Foster appeared to be on his way out of Pittsburgh in the offseason. He was a free agent, and he said in January that he wanted to play somewhere where he was "appreciated." The Steelers gave him a three-year token of appreciation. Foster had some awful games, including the Titans game -- Figure 1 was not his only bad block. His awkward lateral blocking makes him the biggest question mark on the line.

Marcus Gilbert, left tackle: Gilbert did not allow a sack in six games at right tackle before suffering a knee injury, but "sacks allowed" can be a misleading metric. He got flagged for holding twice against the Jets, and Roethlisberger made Gilbert look better by slipping away from a pair of likely sacks against the Eagles. The Steelers have been planning to move Gilbert from right to left tackle for two years, but something always goes wrong: Gilbert gets hurt, or he gets benched for skipping a team meeting, or the Steelers just get cold feet. Max Starks is gone, and Mike Adams' hospitalization this weekend erases any lingering chance that the Steelers might have kept Gilbert on the right and inserted Adams on the left.

Mike Adams, right tackle:  Adams was stabbed this weekend while trying to stop the theft of his truck. The assailant did not cause critical injuries, and Adams was recovering at press time. He is expected to miss about six weeks of football activities, putting him on pace to be ready at or near the start of camp if all goes well.

Adams looked lost at the start of training camp last year. He worked his way up the depth chart as much because of the injuries and ineffectiveness as others as his own improvement. Like DeCastro, he had a few "Help! I'm a rookie!" games late in the year before suffering an ankle injury. Adams, last year's second-round pick out of Ohio State, is a specimen: 6-foot-7 and change, long arms, a thick frame that looks perfectly proportioned at 325 pounds. He's a little sluggish off the line, however, and his fundamentals need work. Adams is exactly the kind of tackle zone-blocking teams avoid: The system is built for smaller, quicker, ornerier players. Assuming a smooth recovery from his attack, he will have to adjust.

Bench: Newcomer Guy Whimper, a former Jaguars starter, is certainly quick: The Jaguars used him as an extra tight end at times and threw him a few passes. Unfortunately, quickness is Whimper's only asset, as he is mistake prone and gets pushed around. Kelvin Beachum, a seventh-round pick last year, got a handful of starts at right tackle during all of the shuffling. He fits the smaller-quicker zone blocking profile and could start at guard or right tackle in a pinch. Doug Legursky, Pouncey's designated backup for years, rebounded from the Titans game to play very well in spot duty last year (Pouncey moved over to guard once or twice to quell crises, with Legursky taking over at center), but Legursky is currently unsigned. The Steelers will probably bring him back; Adams' injury, which creates a depth domino effect, could be the catalyst.

The Verdict: The Steelers' offensive line is younger -- and has far more potential -- than it was with Starks and Willie Colon holding down starting jobs. Potential can be a dirty word, of course, and a lot rests on DeCastro and Adams, two fine prospects who showed very little in 2012. Haley, with Bicknell's help, can silence some doubters by developing this offensive line.

Haley and Bicknell are not the only ones who have some adjusting to do. Steelers head coach Mike Tomlin, who is usually not too involved in the offense, was also part of the problem last year.

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Coach Mike Tomlin (left) and offensive coordinator Todd Haley will try to reinvent the team's ground game. (USA TODAY Sports)

The Coaches

Some coaches believe that when a running back fumbles, he needs to go right back out on the next series and get a few carries so the fumble does not linger in his mind. Mike Tomlin is not that kind of coach.

Dwyer fumbled in the second quarter of Week 3 against the Raiders. It was his last carry for a month. He fumbled in the second quarter of the Browns game in Week 1 and reappeared for one more fourth-quarter carry only because there are only so many spots for running backs in Tomlin's Thinking Chair.

Mendenhall fumbled earlier in that Browns game, which is why Dwyer was out there. He fumbled later in the game, too, which led to a midweek drama. Tomlin called the running back out, Mendenhall skipped practice, and that was all we saw of Mendenhall for a while.

Redman fumbled in the first quarter of Week 10 and disappeared for a half, reappearing late in the game to spell Dwyer. He fumbled again in Week 12. That makes four fumbles in the Week 12 Mistake by the Lake loss to the Browns: Mendenhall, then Redman, then Dwyer, then Mendenhall again. Rainey carried five times in the game as Tomlin, Haley and the Steelers searched in vain for someone who could hang onto the football. It was the ultimate running game failure, it resulted in a loss to a beatable opponent and it helped knock the Steelers out of the playoff picture.

Haley gets a lot of criticism here at Mandatory Monday, and he has a compulsion for juggling running backs. In Kansas City, the shuffling grew comical at times: Jamaal Charles would take one carry, then Thomas Jones the next, then Charles, then Jones, and you wondered if Haley noticed that Charles was at least twice as productive as Jones, or if he cared.

There was a lot of silly juggling in Pittsburgh last year, too. Every week there was a new paradigm: Redman as third-down back, Rainey as third-down back, Redman as goal-line back, Dwyer as starter, Dwyer as change-up, backfield-by-committee, go-with-hot-hand, feed-Mendenhall-until-he-gets-comfortable, and on and on. Against the Cowboys, Redman came off the bench in the third quarter of a game where Dwyer was useless, broke multiple tackles for a 23-yard run … then promptly returned to the bench, earning just two more touches the rest of the game as Dwyer resumed every-down duty.

But the fumble doghouse was Tomlin's real estate. He benched Dwyer after the Titans game by posting an announcement on a bulletin board. The Mendenhall situation got unnecessarily out of hand. Rainey admitted after the Browns game that he did not expect to play on offense at all in the game. At one point, he was the goal-line back: a tiny, troubled rookie plunging the line with his team trailing a division opponent on the road late in the season with the playoffs at stake and three healthy big backs on the bench. (Rainey scored, but still …)

Tomlin's post-fumble strategy has to be re-evaluated. There were too many Batch and Rainey sightings as Dwyer, Redman and Mendenhall did penance. Mendenhall was too good a player, and worked too hard to return, to suddenly become an outsider. There's a difference between a running back playing with a healthy urgency to keep his job and one terrified to make a mistake. Steelers backs crossed that line in Cleveland.

As for Haley, he coached some very effective running games in Kansas City, though a Haley Skeptic has to wonder how much better those running games would have been without worn-out Jones and Larry Johnson leeching carries from Charles. (Yes, Charles is small and proved injury prone, but there is no excuse for the amount of action Jones saw in 2010 while Charles averaged 6.4 yards per carry.) He had a lot of success in Kansas City with plays like the one in Figure 1: The Chiefs' guards and H-backs were good at pulling and sealing holes for Charles to scoot through. Haley often comes across as obstinate, prickly and even a little nuts, but Bicknell's presence and the new blocking principles demonstrate a willingness to change.

Tomlin will have to change a little too. He will be relying on a rookie and two guys who spent time on his naughty list last year to carry the ball. He cannot go into mass-benching mode the first time the ball hits the ground.

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Le'Veon Bell ran for 1,793 yards and 12 touchdowns for Michigan State last year. (USA TODAY Sports)

The Opportunity

Steelers offensive players broke 76 tackles last year, according to Football Outsiders. It was the third highest total in the NFL. Redman actually had the highest broken-tackle percentage in the league: 24 broken tackles in 129 offensive touches, or a broken tackle on 18.6 percent of his touches. Dwyer finished fourth, with 29 broken tackles on 174 touches (16.7 percent).

In other words, Redman and Dwyer are pretty good. Imagine if they did not need to break tackles just to get through the line of scrimmage. Imagine if they didn't disappear for two weeks after each fumble. Imagine if Bell, a pretty good tackle-breaker in college, picks up where Mendenhall left off in 2011.

The Steelers have addressed most of the problems that came to a head that afternoon. But they may not have fixed them. There is a lot riding on unproven linemen and a new blocking scheme. Some successful coaches must accept that they are part of the problem.

Still, the opportunity is there. No team is better at this kind of buttoned-down, low-cost, under-the-hood style of improvement than the Steelers. They draft wisely and develop players carefully. They take the long-range approach on players like Dwyer and Foster, players other teams would have soured upon last year. If they fix the running game, they can be right back in the playoff picture. If they can make it great, admittedly a much tougher task, they can be right back in the Super Bowl picture.

But they cannot afford another failure like 2012. If that happens, a disgruntled running back and some aging linemen won't be the only ones leaving town.