.vresize.36.36.medium.0.png){kind=small}
.vresize.36.36.medium.0.png){kind=small}
CHAPEL HILL, N.C. (AP) Charlton Warren saw plenty of ability in the defensive backs he inherited at North Carolina. The Tar Heels assistant coach just had to fix their techniques and fundamentals after they were part of the worst statistical defense in program history last year.
That work is maybe the biggest reason for the No. 21 Tar Heels' defensive turnaround.
UNC ranks among the national leaders in passing yardage and passing efficiency defense as well as overall scoring defense heading into Saturday's rivalry game with Duke. And that has the Tar Heels (7-1, 4-0 Atlantic Coast Conference) sitting alone as the only unbeaten team in the league's Coastal Division standings.
''To their credit, they really bought into that (teaching) and changed everything they did about themselves as a defensive back,'' said Warren, the position group coach. ''There was resistance obviously initially: `I've been doing it for so long, Coach.' It didn't really matter.''
The change has been dramatic. The Tar Heels surrendered program records of 6,472 yards (497.8 per game) and 507 points (39 per game) last season, leading to an overhaul of the defensive staff that started with the hiring of former Auburn head coach Gene Chizik as coordinator.
While the entire defense has been better, the play in the secondary stands out. After repeatedly giving up big gainers and constantly being out of position, the Tar Heels' defensive backs are now are routinely right with receivers to make spot tackles or a break on the ball.
Cornerback Des Lawrence is tied for 13th nationally with nine breakups. North Carolina has 33 on the season, good for 30th in the Bowl Subdivision, according to STATS.
''It's just all about getting to a hip and then as you feel comfortable getting your head around,'' Lawrence said. Warren ''got us comfortable with getting to the hip and then making a play on the ball.''
As a result, UNC enters the game ranked third nationally in fewest passing yards allowed (152.9 per game) and 13th in passing efficiency, part of an overall unit ranked 16th nationally in scoring defense (17 points per game).
''Their back end has just been outstanding,'' Duke coach David Cutcliffe said. ''Their corners and their safeties and backers just prevent big plays in the passing game, and then their safeties have done a good job even with people who have had a little success running the ball, but it hasn't generated a lot of long, long runs.''
Warren, one of three other new defensive assistants, spent nine years at Air Force and a year at Nebraska before arriving in Chapel Hill. He said he occasionally sees moments when bad habits creep back into the play of his position group - and corrects them immediately.
''Everything ain't going to be a pick,'' he said. ''Some things are going to be a pass breakup and some things are going to be a tackle. You've got to have the instincts to know when that play is going to happen.''
At Duke, Cutcliffe said Thursday morning that running back Shaun Wilson won't play due to a lower-leg injury suffered last week against Miami.
---
AP Sports Writer Joedy McCreary in Durham contributed to this report.
---
Follow Aaron Beard on Twitter at http://www.twitter.com/aaronbeardap and the AP's college football site at http://collegefootball.ap.org .
