Tackles headline 2009 O-line group

Last year's top overall pick, OT Jake Long, was a more complete prospect when he left Michigan for the NFL than any offensive lineman in the 2009 class. That's not to say this year's crop is void of superior talent, however. In fact, there appear to be at least three tackles gifted enough to step into full-time roles as rookies and blossom into upper-echelon NFL starters for many years. Baylor's Jason Smith is a former tight end with great feet and toughness, Virginia's Eugene Monroe is a smooth technician ideally suited for a pass-heavy system, and Alabama's Andre Smith is the dancing bear of the group whose poor pre-draft decisions have overshadowed his immense potential.

While it won't stretch eight deep like it did in 2008, there could be another first-round run on offensive tackles due to lack of supply for the enormous demand. That bodes well for Mississippi's Michael Oher, Arizona's Eben Britton and Connecticut's William Beatty, who make up the second tier of talent at the position. Like Andre Smith, Oher possesses excellent feet for his size but motivation issues and inconsistent play mean drafting him in the first round is a high-risk proposition. Britton looks the part of a mauler but his game is built more on finesse than power. And Beatty is a bit too soft for our liking, but much like Duane Brown a year ago Beatty has the raw athleticism to land a spot late in the first round.

One of the greatest weapons in an NFL offensive tackle's arsenal is his length. Why? Because the difference between a sack and a completion can be a split second, and tackles with long arms force edge rushers to take a wider angle to the quarterback. As a result, players who lined up at offensive tackle in college but lack the desired arm length and/or height to play there in the NFL often fit better on the inside. Which brings us to our top guard prospect, Oregon State's Andrew Levitre.

While the 6-foot-3 Levitre lined up at tackle for the final three years of his collegiate career, he would have a difficult time protecting the edge in the NFL. On the flip side, he's more than capable of holding his own working against interior pass-rushers and he has the tenacity to quickly develop into an effective interior drive blocker.

After Levitre comes a more conventional guard prospect in 329-pound Duke Robinson of Oklahoma. Robinson is big enough to engulf undersized defensive tackles and he moves surprisingly well for a player his size. It's unlikely he will hear his name called on Day 1 but he shouldn't have to wait long into Day 2.

There is a considerable drop-off after Levitre and Robinson but there are some intriguing middle-round prospects, and Auburn's Tyronne Green is one of them. Green makes up for his lack of overwhelming size and prototypical strength with quickness and resolve. He impressed Scouts Inc. as well as several NFL teams with a strong showing at the Senior Bowl.

Keep an eye on Cincinnati's Trevor Canfield as well. A 2008 arrest raises a character flag and his marginal athletic ability puts a lower cap on his upside, but Canfield has the strength and mean streak most teams covet at guard.

Another offensive guard prospect worth mentioning here is LSU's Herman Johnson. Considering he's a three-year starter from the SEC who weighed in at 364 pounds at the combine, Johnson certainly has the size and credentials teams look for in a first-day guard prospect. The problem is, at 6-7 Johnson has a difficult time staying low and driving defenders off the ball and, in our opinion, he isn't athletic enough to move to right tackle.

Three centers have come off the board in the first two rounds twice in the past six years, and don't be surprised if California's Alex Mack leads a similar charge again this year. Mack is a relentless drive blocker who plays with tremendous leverage and can hold his own in pass protection. In other words, he's capable of competing for a starting job as a rookie, and he's not the only center we think is ready to make the jump to the NFL.

Oregon's Max Unger didn't perform as well as Mack at the Senior Bowl but the former offensive tackle is a technician who gets into position and sustains blocks once he's locked on. Unger makes up for what he lacks in athletic prowess with tenacity and smarts. Meanwhile, strong performances at the Senior Bowl and the combine have propelled Louisville's Eric Wood, the No. 3 center on our board, into the first-day conversation. He is another blue-collar player who has impressed scouts with his toughness and smarts.

There is a clear drop off after the top three but Antoine Caldwell is making a late push to move into the third round. Caldwell isn't the most graceful athlete or an overwhelming drive blocker but he almost always finds a way to get the job done.

Projected middle-round picks Jonathan Luigs of Arkansas, of Alabama and A.Q. Shipley have flaws that prevent them from being considered first-day prospects but they also have ample experience playing at the highest levels of collegiate football. They should develop into effective backups at the very least. They should develop into effective backups at the very least. In fact, Luigs could develop into a quality starter and prove to be steals three-to-four years down the road.

To see which players Scouts Inc. thinks are the best of the guard and center classes, those who could become midround sleepers and which offensive linemen are the best in areas such as pass blocking, run blocking, and overall strength and toughness, become an ESPN Insider. Insider