Editor's note: This is the fourth in a weekly series detailing the top senior prospects, by position, for the 2011 NFL Draft.
Did you know?
» [Reggie White](http://www.nfl.com/players/reggiewhite/profile?id=WHI419940)'s number 92 was retired by two teams, the [Philadelphia Eagles](/teams/philadelphiaeagles/profile?team=PHI) and [Green Bay Packers](/teams/greenbaypackers/profile?team=GB).
» Only two positions (quarterback and running back) have had more players drafted first overall than defensive linemen.
» At one time, defensive linemen were one of the lowest paid positions. That's changed over the years, especially with the contracts for Albert Haynesworth and Julius Peppers the last two offseasons.
To win games, and ultimately championships, teams must be able to stop the run and pressure the passer, which is why defensive line talent is so important. Much like the 2010 draft class offered defensive line depth, the list of front four prospects for 2011 is also deep.
The trickledown effect of a solid defensive line can be immense, including helping defensive backs in coverage.
To be a good defensive tackle you need great quickness (Chicago's Tommie Harris), functional football strength (Baltimore's Haloti Ngata), instincts (Dallas' Jay Ratliff), the ability to use one's hands to shed blockers and the athletic ability to drop into coverage on zone blitzes. To be effective, defensive tackles need to have great stamina and be able to rush the passer late in the game, especially in warm weather early in the season. Many teams use a rotatation on the interior of the line to keep players as fresh as possible.
More and more, teams are looking for linemen who thrive in a 3-4 scheme. In 2001, only one team played a 3-4. In 2007, more than 10 teams used the 3-4 as one of their defenses. In 2010, the figure will jump to about 16, with the Washington Redskins among the teams making the switch. The 12 teams that played in the last six Super Bowls have all had very good defensive lines that produced lots of sacks. Only four of the 12 had less than 40 sacks (2006 and 2009 Colts, 2008 Cardinals and 2009 Saints). The 2007 Giants and 2008 Steelers each had over 50 sacks during the regular season.
For defensive ends, size and long arms are needed on the strongside, while speed is a key trait on the weakside. Defensive ends who can apply pressure from the quarterback's blindside (Minnesota's Jared Allen) are a real asset.
This look only includes players who will have exhausted their eligibility after the 2010 season. Nebraska's Jared Crick redshirted in 2007 and has two years of eligibility left as does Wisconsin's J.J. Watt. For that reason they weren't included on this list, but they would likely be top prospects if they chose to enter the 2011 draft.
Here are the top 17 senior defensive linemen that scouts will be keeping a close eye on this fall.
Top senior defensive linemen
1. Adrian Clayborn, DE
Height/Weight: 6-3, 287
He put up 11.5 sacks and 20 tackles for loss last season. He also showed up on the big stage, helping Iowa beat Georgia Tech in the Orange Bowl. Clayborn has all the traits to be a very good player and is an outstanding person. He should go in the top 10 of the 2011 draft.
2. Allen Bailey, DE
Height/Weight: 6-4, 290
He plays end, but has the versatility to move inside and rush the passer on some third-down situations. Bailey's started a total of 14 games over the past years with 12 sacks and 20 tackles for loss. His play earned him first-team All-ACC honors last season. He's got everything you want in a defensive lineman: Speed, quickness and strength. He'll go in the first round next spring and play in the league for a long time.
3. Greg Romeus, DE
Height/Weight: 6-5 1/8, 270
End with great upside. He played only one year of high school football after being considered a college basketball prospect. Romeus posted 19.5 sacks over the past three seasons. He has the speed and athleticism to succeed, but needs to add strength. However, he'll still go in the first round and has great potential.
5. Stephen Paea, DT
College: Oregon State
Height/Weight: 6-1 3/8, 306
A native of New Zealand, Paea grew up in Tonga playing rugby. He did not learn to speak English until he was 16. Paea is strong (he can bench press 225 pounds 44 times) with great quickness for a defensive tackle. Considering his lack of experience, Paea is very mature on the field. He has played in 26 games over the past two years. He's destined to become a first-round pick and should play at a high level for many years.
6. Jeremy Beal, DE
Height/Weight: 6-3, 265
Pass rushing skills produced 20.5 sacks over the past three seasons, including 11 a year ago. Originally began as a linebacker, but was converted to defensive end. Definitely takes advantage of Oklahoma's weight program, which is built for quickness and not bulk. Has the ability to run in the 4.75 range in the 40-yard dash.
7. Ryan Kerrigan, DE
Height/Weight: 6-4, 260
He led the Big Ten with 13 sacks last season, which ranked third in the nation, to go with seven forced fumbles. Kerrigan broke his foot in the season finale against Indiana. He has a big-time motor and never lets up.
8. Jabaal Sheard, DE
Height/Weight: 6-3, 255
He's started in 26 games over the past two seasons and produced 10.5 sacks over that span. He possesses the speed and quickness to get after the quarterback. He helped an elderly woman escape from a burning home in Florida while he was in high school.
9. Sam Acho, DE
Height/Weight: 6-3, 260
Smart, athletic player whose best football is ahead. Acho played at a small private high school. Consistently plays hard and will make a solid pro. Both of his parents were born in Nigeria.
10. Pernell McPhee, DE
College: Mississippi State
Height/Weight: 6-2 3/4, 277
McPhee had 33 sacks in two seasons as a defensive end at junior college in 2007 and 2008. He's a good pass rusher with the speed and size to be an effective defensive end.
14. Kenrick Ellis, DT
Height/Weight: 6-5, 335
Began his college career at South Carolina, but transferred to Hampton in 2008 and has started the past two seasons. Ellis has great strength.
15. Adrian Taylor, DT
Height/Weight: 6-4, 300
Taylor has started 27 straight games, but suffered a dislocated ankle in last season's Sun Bowl win. Is a good pass rusher who will be watched to see how he plays without Gerald McCoy taking up attention.
16. Pierre Allen, DE
Height/Weight: 6-4, 265
Originally came to Nebraska at 230 pounds. Allen was named Mr. Basketball as a high school player in Colorado. End with good strength and speed, but had back problems last season.
17. Ian Williams, DT
College: Notre Dame
Height/Weight: 6-1 1/2, 305
As nose tackle for the Irish, Williams started two games as a true freshman in 2007 and 17 total over the last three years. He is very strong and powerful, especially against the run, but he needs work as a pass rusher.