SI 64: No. 1: USC DT/DE Leonard Williams

What is it about USC defensive tackle Leonard Williams that lands him the No. 1 spot on our SI 64 prospect countdown?

With the 2015 NFL draft fast approaching, it’s time for all 32 NFL teams to start getting their draft boards in order and ranking players based on their own preferences. At SI, it’s time for us to do that as well. To that end, Doug Farrar and Chris Burke have assembled their own definitive Big Board, consisting of the players they feel deserve to be selected in the first two rounds.

And so we reach the final curtain.

What is it about USC defensive tackle Leonard Williams that lands him the No. 1 spot on our SI 64 prospect countdown? The answer is not so much about what Williams does well (a lot, as we'll get to soon), but rather about how little in his game leaves scouts wanting.

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That on its own may not sound like much, but consider this draft class. Seahawks GM John Schneider told The MMQB that at the time he traded for Jimmy Graham in early March, he had just 16 prospects with first-round grades. Among the names that we can assume are up there, questions linger about any number of topics: weight, experience, ability to translate to the NFL level, technique.

Williams is not a finished product either, and his game has distinct areas where it needs improvement. His apparent floor, though, projects him out as a better player than the majority of 2015's prospects. Should he ever unlock his full potential, Williams has the skills and physical attributes to be one of the league's dominant defenders.

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"I do believe I’m a great player," Williams said at USC's pro day, per Redskins.com. "And I’m not going to brag and boast about myself, but if it comes down to a team asking me, I’m going to tell them you got your pick."

Williams actually did not begin playing football until high school because, as he tells it, "I was too big for Pop Warner. There was a weight limit and I was above it."

It did not take him long to draw some attention once he did take the field. In addition to USC, Williams received scholarship offers from Alabama, Florida, Clemson and others. He started nine games as a true freshman for the Trojans, then wrapped his career by being named USC's Most Valuable Player in 2014.

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Strengths: A defensive lineman standing 6'5" and 302 pounds should not possess the explosive quickness Williams puts on display. USC could slide Williams along the line because he has the athleticism to play several spots—true to DT form, Williams shoots gaps inside, but he also can turn the corner when shifted further outside.

"I'd rather move around the whole D-line than stay in one spot the whole time," Williams said at the combine. "It was more fun to create matchups and be able to go against some weaker opponents every once in a while. When the coaches switched it up for me, I liked it."

Despite battling ankle and shoulder ailments last season, Williams finished with 80 tackles, 9.5 tackles for loss and 7.0 sacks. In 2013, a season in which he admitted playing at about 65%, Williams registered 13.5 tackles for loss and 74 more tackles.

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His speed off the ball helped him rack up all those stats. His power when facing offensive linemen head-on is what pushed Williams over the top. During that same combine interview, he said that his ideal position would be as a four-tech, head up on the tackle. Williams rarely cedes ground in those situations, usually winning battles by driving blockers back toward the quarterback or running back. When he can get his hands into the chest of an offensive lineman, he's borderline unblockable, with the motor to stay alive if he fails to land the first blow.

The toughness factor should fare well in NFL war rooms, too. Williams played through a torn labrum during that '13 season and started all 13 games last year, even while hobbled at times.

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Weaknesses: The most prevalent critique of Williams's game—that he likely will not be a great pass rusher early in his NFL career—ties in more to his projected draft spot than anything else. Defensive tackles taken in the top five are expected to lead the charge on all three downs; Williams shapes up as a two-down force who will have up-and-down production against the pass.

An assist from his next coaching staff will help. Right now, Williams does not consistently show the power or anticipation when chasing the quarterback that he does against the run. While he's not easy to block in passing situations (see: 21.0 career sacks in three seasons), he is not a total nightmare for offensive linemen the way he is on run plays.

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The injuries are another potential concern. Williams required surgery on his torn labrum following the 2013 season and has had labrum issues in both shoulders, which is why he did not lift at the combine. Add in last season's high-ankle sprain, and Williams was banged up a lot over the past two years. That he played through those injuries will work in his favor, but NFL front offices still have to figure out if his health will be a long-term problem.

Conclusion: Tampa Bay's urgent need for a quarterback could lock Williams out of the No. 1 pick. It should not prevent him from being considered there, and several teams will be waiting to pounce should the Buccaneers pass. Williams is as NFL-ready as any 2015 prospect and offers an All-Pro ceiling.

We've seen entire defenses built around recently-drafted linemen: the Texans with J.J. Watt, the Lions with Ndamukong Suh, the Bucs with Gerald McCoy. Assuming Williams will match any of those players' impacts is setting the bar extremely high. He is capable of getting there.

Player comparison: Gerald McCoy, Buccaneers (Round 1, 2010)