The rise of spread offenses and the different schemes teams face on a week-to-week basis in a college football season has altered how some defensive coordinators think. While some are placing more emphasis on building a secondary, the success of any defense starts up front. Generating a pass rush and stopping the run are two staples of any defensive scheme.

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How did we come up with these rankings? A couple of factors were considered. Depth, overall talent, production, level of competition and projected output in 2015 all factored into the rankings for the backfield. While some teams may have experienced a down year last season, having a different quarterback or a change of scheme can make a huge difference. These rankings reflect projection for 2015, not solely what teams have accomplished in 2014.

College Football's Top 35 Defensive Lines for 2015

Nearly everyone from a dominant 2014 group is back for coordinator Kirby Smart. The Crimson Tide allowed only five rushing scores last year and limited opponents to 3.2 yards per carry. A’Shawn Robinson won’t post huge numbers, but the junior is versatile enough to play on the outside or on the interior and is the top player in this unit. Ends Jarran Reed and Jonathan Allen played in all 14 games and combined for 17.5 tackles for a loss last year. Helping the starting trio is a deep and experienced group of reserves, including D.J. Pettway and 2014 five-star recruit Da’Shawn Hand.

An aggressive and deep defensive front is becoming an annual storyline for Michigan State. The Spartans have ranked among the top 10 nationally in rush defense in four consecutive seasons and finished first last year by holding opponents to just 88.5 yards per game. Shilique Calhoun decided against entering the NFL Draft for one more season in East Lansing, and the senior is a first-team Athlon Sports All-American. Senior Lawrence Thomas slides from tackle to end, but sophomore Demetrius Cooper and redshirt freshman Montez Sweat will push for snaps. The interior is set with Malik McDowell and Joel Heath.

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Virginia Tech’s offense remains a work in progress, meaning the Hokies have to ask their defense to carry this team once again. Fortunately for coordinator Bud Foster, that won’t be a problem with eight returning starters and the best defensive line in the ACC. The Hokies allowed 144.8 rushing yards per game last season, but that number should decrease with the return of Luther Maddy from injury at tackle. And the rotation on the interior is set with Nigel Williams, Corey Marshall and Woody Baron. The Hokies could have the nation’s top duo at end with Dadi Nicolas and Ken Ekanem. True freshman Tim Settle is another name to watch.

Baylor’s high-powered offense garners all of the attention, but the defense has made considerable progress under coordinator Phil Bennett. The Bears held opponents to 3.2 yards per carry last year and ranked 16th nationally against the run. At 6’9” and 280 pounds, end Shawn Oakman is as physically gifted as any defender in the nation. He recorded 11 sacks last season. End Jamal Palmer is back as a starter on the other side after missing most of 2014 with a torn ACL. The interior is stout with senior Beau Blackshear and the underrated Andrew Billings back in 2015.

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Even though the Rebels lose three contributors from last year’s line, this group could be deeper and better than it was in 2014. Tackle Robert Nkemdiche earned first-team All-SEC honors last season, and the NFL prospect is primed for his best year as a junior. Issac Gross joins Nkemdiche as a disruptive force on the interior, with junior college recruit D.J. Jones supplying depth. Freshman Victor Evans and junior Fadol Brown are expected to start on the edges, but sophomore Marquis Haynes should see an increased role after leading the team with 7.5 sacks in 2014.

The defending national champs have a few losses to address up front. Standout tackle Michael Bennett departs after recording 14 tackles for a loss and seven sacks last season, and the Buckeyes must find a new starter at end after Steve Miller and Rashad Frazier expired their eligibility. While two new starters join the lineup, this unit still features Joey Bosa – arguably the nation’s No. 1 player – and senior Adolphus Washington at tackle. The Buckeyes have plenty of options and talent to fill the voids up front, so a drop-off in production should be minimal.

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Another year, another strong defensive front for coach Gary Patterson. The Horned Frogs suffocated opposing offenses with an aggressive defensive front in 2014, holding rushing attacks to just 108.8 yards per game and recording 39 sacks in 13 games. This year’s line returns three starters from 2014, with tackle Chucky Hunter the lone departure. Ends James McFarland, Terrell Lathan, Mike Tuaua and Josh Carraway return after combining for 18.5 sacks in 2014. Aaron Curry, Chris Bradley, Tevin Lawson and Davion Pierson form an effective and talented group of options at tackle.

While the offense has its share of question marks, Florida’s defense should be among the best in the SEC in 2015. The Gators return seven starters, including two in the trenches with senior Jon Bullard and junior Bryan Cox Jr. Junior Alex McCalister is poised for a breakout season after generating six sacks in a reserve role in 2014. Touted true freshman CeCe Jefferson will also see snaps in the end rotation, as the line looks to replace the production lost by Dante Fowler’s departure to the NFL. Sophomore Caleb Brantley and redshirt freshman Taven Bryan are two names to watch on the interior. The Gators held opponents to just 116.2 rushing yards per game last season.

With eight returning starters and a year of experience under coordinator Marcel Yates, the Broncos’ defense is poised for big improvement on the stat sheet. Each of the three units on defense could be among the best in the nation, but the success of this group starts up front. End Kamalei Correra returns after recording 12 sacks last season, and senior Tyler Horn returns after missing nearly all of 2014 due to injury. The Broncos ranked fifth nationally after recording 47 sacks last year.

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A similar theme is set to unfold in Austin this season. The Longhorns should be stout on defense, but the offense will be a work in progress. The strength of Texas’ defense is located up front, where junior Hassan Ridgeway and sophomore Naashon Hughes are back as returning starters. Desmond Jackson’s return from injury and Poona Ford’s continued development will help the Longhorns remain strong at the point of attack. Junior college transfer Quincy Vasser, senior Shiro Davis and junior Bryce Cottrell are more options for coach Charlie Strong at the defensive end spot.

11. Auburn

12. Tennessee

13. Penn State

14. UCLA

15. Utah

16. LSU

17. Texas A&M

18. Notre Dame

19. Arkansas

20. Oklahoma State

21. Florida State

22. Clemson

23. Louisville

24. Boston College

25. USC

26. Nebraska

27. Oklahoma

28. Oregon

29. Michigan

30. Georgia

31. UCF

32. Minnesota

33. Georgia Tech

34. Temple

35. Mississippi State