When Matt Barkley takes the field for USC's pro day on Wednesday, he will not be alone. Matt Leinart, Mark Sanchez and Carson Palmer will be with him. Metaphorically, they follow him every step that he takes.

Barkley will be out to prove that he has fully recovered from the separated shoulder that ended his senior season. Few people doubt that he has fully recovered. Barkley will be out to prove that has an adequate NFL arm. Few people doubt that he has exactly that.

Matt Barkley's most difficult job will be proving that he is Matt Barkley, not Mattson Leinbarkchez, an amalgam of previous USC quarterback disappointments, a copy of a copy of a copy of a copy that fades a little each time. It will be hard to convince anyone that he is more than the latest scion of a disreputable dynasty on Wednesday: Most predispositions are set and minds are made up. As long as Sanchez is a comic figure in New York, Leinart a cautionary tale of taking success for granted and Palmer a limping shadow of a briefly great quarterback, Barkley will be burdened by comparisons.

Every draft needs one enigmatic quarterback. By virtue of his up-and-down, his arm strength and his predecessors, Barkley is this year's designated enigma, even though there is nothing all that puzzling about him.

Agree to Disagree. The consensus opinion about Matt Barkley is that there is no consensus opinion about Matt Barkley. If you poll a half-dozen draft/NFL experts about him, you are supposed to get a dozen different opinions. Yet when I asked some colleagues to give me one-sentence summaries of Barkley (short summaries eliminate hemming, hawing and molecular scout-speak about arm motions, so we could go "big picture"), it sounded like everyone was in agreement, even as they thought they were disagreeing.

Doug Farrar, Yahoo! Sports: "Thank you for purchasing the USC Draft Prospect Operating System!  In the new package, please notice the addition of Matt Barkley 1.0, who looks a lot like Mark Sanchez 2.0 or Matt Leinart 3.0. As with all our quarterback software over the last few years, arm strength is a bug that will hopefully be fixed in future versions. Game intelligence tends to be overrated and should not be mistaken for future productivity. Software will tend to lag severely without at least one elite running back add-on, and at least 2 terabytes of defense."

Andrew Garda, Bleacher Report and FootballGuys.com: "Staying a fourth year at USC got analysts to focus on Matt Barkley's durability, average arm strength and inconsistency on long throws, while pushing aside his great mechanics, excellent short accuracy and great touch."

Peter King, Sports Illustrated: "If you don't allow his 2012 season to overwhelm your opinion of Barkley, you'll conclude he's a solid NFL prospect with all the elements to succeed in the NFL except the cannon arm -- and plenty of quarterbacks have succeeded without said cannon arm."

Russ Lande, National Football Post, Big Ten Network, Author of GM Jr. Draft Guide: "Barkley is a highly intelligent quarterback whose greatest strengths are above his shoulders.  He has a good enough arm to make all the NFL throws, and combined with good mechanics and anticipation is effective making quick, timing based throws.  While he is being dismissed by many, Barkley will likely turn out to be better than most of the quarterbacks in this year's draft because much of an NFL quarterback's success comes down to his smarts, football intelligence and intangibles."

Matt Miller, Bleacher Report: "Barkley is a smart, poised quarterback but lacks the top end physical tools of recent elite prospects."

Kevin Fishbain, Pro Football Weekly: "Barkley has the mechanics for the pro passing game, but his intangibles and experience having to play under the spotlight for his entire college career also help set his potential apart from a lackluster quarterback class."

Rob Rang, CBS Sports, NFL Draft Scout: "While lacking elite physical traits, Barkley possesses the best combination of the 2013 class in the 'Three As' -- awareness, anticipation and accuracy -- which have historically proven to be an effective indicator of future success in the NFL."

Keep in mind that these are experts who do all the homework, go to pre-draft functions, talk to scouts/coaches/executives and watch tape, not personalities who suddenly show up on television in April with a three-piece suit and an opinion. If anyone is shouting "next Peyton Manning" or "Guaranteed Bustburger," they aren't basing their opinion on the weeks of legwork these guys (and others like them) devote to every major prospect.

Only Farrar is highly skeptical of Barkley, though his criticisms address the exact attributes the others mention: awareness and intelligence (strengths), arm strength (weaknesses). Farrar also hints that Barkley could be successful with the help a great running back and defense, though the same could be said of any draftable quarterback.

Everyone else is on about the same page, yet everyone is quick to point out that not everyone is on that page. Garda and King think others are putting too much stock into 2012 but admit that Barkley's skills are lacking. Lande, Miller and Rang give almost identical opinions. Farrar's dissenting opinion focuses directly on the "intelligence" stressed by the others: It's a quantitative argument, not a qualitative one. None of these guys are among the "others" who focus on 2012; Mike Mayock of NFL.com, who ranks Barkley second to Geno Smith among quarterback prospects, is not in that group either. Who does that leave to over-emphasize 2012? Certainly not NFL scouting departments, who have had Barkley on their radar since he left high school.

And this is not groupthink, even though many of us talk to one another and compare notes now and then. Toss Ryan Nassib into the middle of this table, and you won't get variations on the same scouting report. In fact, the table might explode.

Let's put another voice into the mix: Charley Casserly of NFL Network, who compared Barkley to Matt Schaub on "Path to the Draft" this week. Schaub has been a playoff caliber quarterback for several years. He has two Pro Bowl appearances (as a backup/alternate, admittedly) and three 4,000-yard seasons under his belt. He has been an NFL starter for six years. By any accounting except the "Either Super Bowl Champion or Pond Scum" method of evaluating quarterbacks, Schaub has been pretty successful.

Schaub was a third-round pick. You have seen him play at his peak: he's not Aaron Rodgers as an athlete or Drew Brees as a decision maker. How high would you draft a quarterback who was guaranteed to be Matt Schaub, who can succeed, as Farrar notes, with an excellent running back and defense?

That's a philosophical question, one that speaks to both Barkley and our collective quarterback neurosis. Give us a quarterback who earns a "B" in most grade books -- a B or B-minus physically, an A or A-plus mentally -- and we don't know how to classify him, because most of the football world grades quarterbacks on a hard pass-fail system. It's that either-or scale that forces my fellow experts to contrast their similarly mixed praise against a perceived groundswell that placed Barkley in one of the two available categories.

It does not help that Barkley follows two USC quarterbacks who earned positive reviews as prospects but leapt with both feet into the "fail" bin.

Ghosts of California. A draft without a quarterback controversy is like a spring without sunshine. In addition to the designated Enigma, there must be a favorite (Geno Smith), a challenger (Ryan Nassib), a tools guy (E.J. Manuel), a college superstar who "just wins" despite marginal tools (Landry Jones), a cannon arm with little else to offer (Mike Glennon), either an attitude case or a victim of circumstance (Tyler Wilson, the latter) and a sleeper whose name you can invoke when you want to sound particularly in-the-know (Zac Dysert).

Even in years when most of the quarterbacks aren't good enough to play their roles, like this year, we force-fit them: If your theatre company is performing "West Side Story," somebody has to play Riff, even if he's Mike Glennon. When the teams and quarterbacks pair off early like ballroom dance partners, as they did last year, we trolley the camera back and go "epic:" How can Andrew Luck replace Peyton Manning, what kind of pressures will face Robert Griffin in Washington DC, draft coverage by VistaVision.

You get to be the Enigma, like Barkley, if you could have filled any of the other roles. Last September, he was the favorite. When Smith exploded and Barkley's shoulder was fine, he was the challenger. He's not really a tools guy, but he was in position to be the just-wins guy, and had he come out with Luck and Griffin in 2012, he might have been the sleeper.

As for victim of circumstance, both the shoulder injury and the legacy place him squarely there. Our image of the USC quarterback was defined by Leinart and reinforced by Sanchez: laconic California guys, perhaps a little privileged, less-than-starving for success, propped up by a program that surrounded them with the best talent west of the Rockies. Palmer was different -- more talented and more dedicated -- but the Palmer of 2005-06 is a distant memory.

A little digging, some tape study and an interview or two reveal quickly that Barkley, while a Southern California suburbanite who attended the same high school as Todd Marinovich (speaking of ghosts), is no silver-spoon stereotype. A little perspective reminds us that Sanchez was hailed as a gritty leader two years ago. These perceptions are often worth their weight in bathroom tissue.

If Barkley had Luck or Griffin talent, the USC legacy would not matter. But Barkley is just enough like his predecessors on the field to keep reminding you of how good a quarterback can look throwing to Steve Smith, Reggie Bush, Damian Williams or Marqise Lee against Colorado. We also remember how prepared and "finished" those California suburbanites can sound: It's easy to be charmed by young men who grew up in environments that taught them exactly what to say.

But aren't we smart enough to look past these preconceptions, or at least acknowledge that they are a problem to be overcome? My expert colleagues appear to do so: Farrar evokes Sanchez and Leinart more as a one-liner or comic hook than as a real appraisal of Barkley, and most scouting reports I read use other USC quarterbacks to help readers make connections (better in pocket than Leinart, lacks Palmer's tools), not as condemnations. Is Mattson Leinbarkchez real, or is he like Santa Claus for fifth graders, someone everyone thinks everyone else believes in? Are the Ghosts of Trojans Past as illusory as the disagreement over Barkley's strengths and weaknesses? That's the enigma within the Enigma.

Tape Study. There's one highly opinionated draftnik we have not heard from yet: me. I watched tape of several USC games in the last two weeks, reacquainting myself with a quarterback who I watched a lot in 2011 and 2012 but rarely scouted. I tried to keep an open mind, but I had preconceptions from watching and reading about Barkley in the past, and of course I talk draft often with the people listed above and others. Here are my impressions.

First, Barkley's arm is not that bad. The "bad Barkley arm" becomes evident when he throws to the sideline. Passes into the flat take forever to arrive; it was common to see Lee, Robert Woods or another receiver get walloped quickly after hauling in a flat pass or bubble screen because the defense was able to converge while the ball was in the air. That said, he gets mustard on passes to the middle of the field, and he knows how to compensate for his lack of pure velocity when throwing deep.

Barkley uses his touch and timing to throw deeper sideline passes ("deep outs") successfully. He often lobs the ball over underneath defenders toward a spot near the boundary instead of trying to hum a fastball past defenders' ears. To do that successfully, Barkley must throw well before the receiver makes his cut and anticipate where his receiver will be when the ball arrives. It's a delicate needle-threading, and while Barkley was good at it, having two superstar receivers helped, and many deep outs were tipped or contested.

As for deep passes, Barkley is not Joe Flacco, but he can complete passes 40 yards down the field. Again, anticipation, awareness and accuracy, Rob Rang's "three A's," help compensate for arm strength.

Barkley_pass_diagram
A pass to tight end Xavier Grimble against Utah stands out, even though Grimble dropped a would-be touchdown. On the pass in question, Grimble ran a corner route, while the wide receiver on his side of the field ran a short smash (see the figure). The trick to throwing the tight end corner successfully, particularly when you cannot launch rockets, is to recognize the coverage, know in advance that the receiver will be open and pinpoint the spot on the field to drop the football into.

The gray oval in the diagram shows the rough locations of Grimble and his defending safety when Barkley releases the ball. Grimble is not obviously "open" when Barkley throws. But the cornerback on that side of the field is covering the short smash, the other safety is elsewhere, and Grimble is assigned to run away from the defender, who is in poor position to cover a pass into the corner. Barkley's throw drops right into Grimble's arms; the tight end just doesn't haul it in.

The Grimble drop was not an isolated example of Barkley using other skills to compensate for muscle on deep passes. Watch any USC highlight reel, and you will find Barkley throwing to his covered receiver's back shoulder in the end zone or heaving the ball down field a split second before Lee or Woods blows past some flat-footed zone defender. Barkley is great at these throws. The question becomes just how much "compensation" will be necessary in the NFL. Faster, smarter defenders will eat up a lot of Barkley's cushion. Quick thinking and a spot-on pass can beat any Utah safety, but Ed Reed offers far less margin for error.

Which, sigh, brings us back to square one: The arm is somewhere between OK and very good, the mental skills somewhere between rock-solid and exceptional. Barkley does lots of little things well, like slide around the pocket under pressure and throw to his hot receivers on blitzes, but the ghosts of USC quarterbacks past cautioning us not to gush too much about intangibles.

Could Barkley start for a playoff team? Sure. Mark Sanchez did it for two years.

Can he reach the Pro Bowl? With the right supporting cast, no problem: Look at Matt Schaub.

Is he a franchise quarterback? What does that even mean? And don't even whisper the word "elite" in my presence.

Will he be drafted in the first round? Probably. Take a look at some of the first-round quarterbacks of recent years. Teams are more willing to reach for quarterbacks than ever, now that a rookie cap keeps their contracts manageable.

Is Barkley worth a first-round pick? Some of these questions only exist to give us something to talk about before the draft. If you need a quarterback right away, and your system does not need a cannoneer, Barkley makes more sense than E.J. Manuel, about as much sense as Ryan Nassib, and even has merits over the high volatility of Geno Smith. But if you need a quarterback right away in the draft, you may want to question the decision making process that led to your predicament in the first place.

A Simple Riddle. So Barkley will throw on Wednesday, and we will hear that his arm looked "better than expected." People who were never within 1,000 miles of Barkley when he threw will be standing a few yards away, after all. Everything looks better up close. And the weak-arm report has taken on a life of its own since Barkley got hurt in November, and some people will be shocked when he completes a seven-yard hitch.

Unless his shoulder comes unhinged and sends his arm rolling under the bleachers, Barkley will "shoot up draft boards" after his pro day. He will attend private meetings with teams, and the news will be duly overstated. Again, this is largely balderdash. Teams will tweak their own draft boards, and their approximations of other teams' draft boards, but teams have been filing reports about Barkley as a major prospect since 2010. NFL minds about Barkley are 99 percent made up.

It sounds like we have all made up our minds, and we have all reached the same conclusions with differing interpretations. Barkley is the safe, moderate-upside quarterback. How much we like him depends on how much we like safe, moderate-upside quarterbacks. And we would like him better if our images of his USC predecessors, of butt-fumbles, keg stands and premature creakiness, did not cast such an ominous shadow.

Really, there is nothing enigmatic here at all. Or is there? Draft coverage is driven by disagreement. Feel free to disagree.

Meanwhile, on the Tailgater

Looking to take a break from March Madness with more NFL coverage? I have you covered over on the Tailgater. The logjam of Hall of Fame defenders on the free agent market will probably unclog itself this week, but take a look back at that strange moment when some of the greatest defenders of this generation were unemployed. Just how good were Lynn Swann and John Stallworth? Well ... you have to read my countdown of the top wide receivers in Steelers history to find out.

And finally, we are on Month Two of the Darrelle Revis saga, and while there is no news to speak of, there is plenty of coverage. The Random Revis Headline Generator will help you feel like you are staying abreast of the situation. It is just like a Magic 8-Ball, which is perfect, because that very device is an important component of every Jets decision.