A day after a defensive meltdown in a 48-45 loss to Texas, Oklahoma has parted ways with defensive coordinator Mike Stoops, a person with knowledge of the situation confirmed to USA TODAY Sports. The news was first reported by KREF radio host James Hale.

Stoops was an original member of older brother Bob Stoops’ Oklahoma staff, and helped build dominant defenses in the early 2000s before going to Arizona as head coach. He returned to Oklahoma in 2012 and remained on staff when Lincoln Riley succeeded Bob Stoops before the 2017 season. But the Sooners’ defenses never approached their former standards.

Defensive deficiency was the primary reason Oklahoma, despite a record-setting offense, fell short in a College Football Playoff semifinal in the Rose Bowl last season. The loss to Texas could be a debilitating blow to the Sooners’ hopes of returning to the playoff.

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The 48-point output was the highest scored by Texas in the history of the heated rivalry. Oklahoma currently ranks 96th nationally in total defense, allowing 421.2 yards a game, and 125th in red-zone defense: In 21 chances, opponents had scored 21 times (18 touchdowns and three field goals).

Texas entered the annual game with Oklahoma after scoring only 10 offensive points in a win against Kansas State. The Longhorns ranked 79th nationally in total offense and 73rd in scoring offense, but piled up 501 yards, averaging 6.7 yards per play. Not counting a one-play possession to end the first half, Texas scored on its first five possessions and built a 45-24 lead. When the Sooners stormed back to tie late in the fourth quarter, the Longhorns moved 52 yards in nine plays for the winning field goal.

“I’m extremely disappointed in my ability to get this team to play at a higher level,” Mike Stoops told reporters Saturday. “It takes everybody pulling the same way. Certainly I take a lot of that responsibility, that’s for sure.”

Oklahoma announced Monday assistant head coach Ruffin McNeill would serve as defensive coordinator, a role he had at Texas Tech before being hired as head coach of East Carolina. Riley

experience as a defensive coordinator, as does Bob Diaco, who is on staff as a defensive analyst.