LOS ANGELES -- Departing USC Trojans assistant coach Monte Kiffin made the decision to leave the team entirely on his own, he said Friday.
Kiffin said his son Lane -- his boss and USC's head coach -- had nothing to do with his resignation, which was announced in a statement released by the school Thursday evening.
"The head coach did not put me under fire," Monte Kiffin told hosts Mark Willard and Ramona Shelburne in an interview on 710 ESPN Radio on Friday. "Nor did [athletic director] Pat Haden or anybody like that.
"And that's the truth. It really is."
The 72-year-old Kiffin, who will resign after the Trojans' December bowl game, said he passed on multiple opportunities to return to the NFL in January to "go for it another year" at USC. But with the Trojans starting the season as the preseason No. 1 and ending the season out of the Top 25 entirely, that final year ended up being a "little bit of a roller coaster," he said.
"It didn't work out," Monte Kiffin said. "Nobody feels worse than I do, and I totally accept that responsibility, being the defensive play-caller and all.
"We didn't play well enough."
USC's defense held four of its first seven opponents to 14 or fewer points in 2012, then totally imploded. Over the final five games, four of which were losses, the Trojans' spread-heavy opponents averaged nearly 36 points per game.
The defense's worst effort came in a 62-51 home loss to Oregon, during which the Trojans allowed the Ducks to gain 730 yards and score nine touchdowns, both records for USC opponents.
"You can't score 51 points and lose," Kiffin said. "That's not right."
Lane Kiffin has been heavily criticized for failing to reach expectations at USC. The Trojans' 7-5 regular-season record likely has them headed for the Hyundai Sun Bowl, a New Year's Eve matinee game, in El Paso, Texas.
Monte Kiffin repeatedly emphasized that he did not see a need to vouch for his son's performance as a head coach. But he praised his son's recruiting abilities on more than one occasion and cited former USC coach Pete Carroll as another believer in Lane's offensive play-calling abilities.
"He's a great recruiter; he communicates with the players," Monte Kiffin said of his son. "He's an excellent offensive coach."
Monte Kiffin spent three seasons as USC's de facto defensive coordinator under the title of assistant head coach. He also worked with his son during the 2009 season at Tennessee.
The elder Kiffin has spent the bulk of his 47-year coaching career as an NFL assistant.