Warren, 38, worked as Nebraska's secondary coach in 2014 after nine seasons at Air Force, including his final six as defensive coordinator. The Cornhuskers ranked second nationally in opponents' completion percentage (48.5), fourth nationally in pass efficiency defense (104.8) and 32nd in passing yards allowed (205.8 ypg) last season.
Warren's secondary delivered elite-level production at Air Force before struggling during his final two seasons. The Falcons ranked second nationally in passing yards allowed (147.8) in 2010 and third in that same category (166.8) in 2011. In 2012, Warren's squad allowed 210.6 passing yards per game (35th nationally) and ranked 107th in pass efficiency defense (147.9). In 2013, the Falcons ranked 78th in passing yards allowed (239.7 ypg) and 124th in pass efficiency defense (170.7).
Warren coached the secondary throughout his nine seasons at Air Force, and held the title of recruiting coordinator for the first six.
He was the only member of Bo Pelini's staff in Lincoln that was retained by Mike Riley this offseason. Warren, who was selected as one of the Big Ten's top recruiters in 2014 by Rivals.com, was considered the key transitional link in Nebraska's ability to sign the nation's No. 33 recruiting class last week.
Warren played defensive back at Air Force ('95-98) during the same period that Fedora served on Fisher DeBerry's offensive staff ('97-98) in Colorado Springs. He won Air Force's Mr. Intensity Award as a senior in 1998.
Warren becomes the third defensive coach added to UNC’s staff since the end of the season.
Defensive coordinator Gene Chizik, who won national championships as a head coach (Auburn) and defensive coordinator (Texas), was hired last month to replace Vic Koenning following UNC’s record-setting 2014 season (39.0 ppg, 497.8 ypg). Former Nebraska defensive coordinator John Papuchis was hired last week as a defensive assistant.
Defensive coordinator/cornerbacks coach Dan Disch and linebackers coach Ron West were also let go in recent weeks as Fedora put Chizik in charge of evaluating UNC's defensive staff and interviewing potential candidates, according to a source.
Defensive line coach Keith Gilmore will remain on staff, according to sources, although defensive position assignments have yet to be finalized.
Papuchis, 36, coached at LSU under Nick Saban from 2004-07 before joining Bo Pelini’s staff at Nebraska in 2008. Papuchis coached the Cornhuskers’ defensive line for three years before being promoted to defensive coordinator his final three years in Lincoln.
"I got a phone call from Coach Chizik and it really became a no brainer for me," Papuchis said last week. "I think we have a lot of the pieces in place here to turn it around quickly and I look forward to doing it."
Warren Hire Completes UNC's Staff
Inside Carolina Top Stories
ICTV: Final Four Send OffFootage of fans cheering on the UNC team as it boarded the bus to head to the Final Four on Tuesday.
Inside CarolinaYesterday at 5:09 PM
Roy Williams PC (Berry Update)UNC's head coach spoke to reporters on Tuesday before the team left for the Final Four in Phoenix.
Inside CarolinaYesterday at 3:30 PM
Williams Driven by CriticismThe Tar Heel head coach remains keenly aware of those who doubt him.
Inside CarolinaYesterday at 1:45 PM
Frasor In His ElementFormer Tar Heel led high school alma mater to first league title since he played for the school 12 years ago.
Inside CarolinaYesterday at 8:02 AM