It's over. USC's latest defensive debacle was too much for Lincoln Riley to continue on with embattled defensive coordinator Alex Grinch.

The day after the Trojans' 52-42 loss to Washington in the Coliseum, Riley made the move fans had been clamoring for and the decision everybody expected had become inevitable.

USC put out a statement just before 12:30 p.m. PT Sunday announcing that Grinch has been fired, and that defensive line coach Shaun Nua and linebackers coach Brian Odom will serve as interim co-defensive coordinators while defensive analyst Taylor Mays has been elevated to an full assistant role and will coach the safeties.

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Over the last six games, USC has given up 44.2 PPG and 483.7 YPG with one disastrous performance being topped by the next and then the next as the Trojans -- once 6-0, ranked in the top 10 nationally and chasing a College Football Playoff spot -- have lost three of their last four games.

It was tough for Trojans fans to watch Utah's third-string, former walk-on QB Bryson Barnes have the game of his life a few weeks ago. It was harder to watch a middling Cal team on its third quarterback of the season put up 49 points and 527 yards last weekend. And it was most excruciating yet seeing USC somehow looking even worse Saturday at home against Washington, as the Huskies piled up 572 yards, including 316 rushing yards for an offense that came in averaging just 102.2 and hadn't totaled more than 177 in any other game.

Washington running back Dillon Johnson, who had never rushed for more than 100 yards in four college seasons, rumbled for 256 rushing yards (9.8 yards per carry) and 4 touchdowns.

In more than 80 meetings over 100 years, the Huskies had never scored more than 34 points in a game against USC -- until they put up 35 in the first half alone Saturday night.

Last season, the first with Riley and Grinch, USC gave up its most yards per game in program history -- 423.9, which well exceeded the previous worst of 408.9 (from the previous year). This season, the Trojans are now giving up 436 yards per game (119th out of 130 FBS teams) and a program-worst 34.5 points per game (121st) and it only figures to get worse next week at Oregon (the top scoring offense in the country at 47.4 PPG).

Riley was asked Saturday night if he regretted how he handled the defense this year -- namely sticking with Grinch after a rough finish to last season and calls from the fan base to make a change.

"I know it's your all's job to ask it, I'm not into the big picture questions right now," Riley said after the loss. "Like, my job's to go try to beat Oregon next week and to coach what we have here. I know as a head coach it all falls under my responsibility ultimately, and I don't shy away from that -- and I never have -- but there's times and places for those discussions and those will happen at the appropriate times."

With time to think about it, Riley decided the appropriate time had indeed arrived.

This is the second time Riley has fired a defensive coordinator in season. The first came in October of 2018, his second season as head coach at Oklahoma, when he dismissed DC Mike Stoops. That led to him hiring Grinch, who had been the defensive coordinator at Washington State from 2015-17 and then the co-DC at Ohio State in 2018.

Grinch delivered immediate improvement as the Sooners went from ranking 114th in total defense in 2018 (453.8 YPG) to 38th (356.4) in Grinch's first season in 2019 and 29th in 2020 (350.6).

The Sooners' defense tailed off in Riley and Grinch's final season at Oklahoma in 2021, ranking 76th (390.8), but there was never a doubt in Riley's mind who would be his DC when he took the USC job. Grinch was one of two assistant coaches along with WRs coach Dennis Simmons who was on the plane with Riley to Los Angeles the morning after he took the Trojans job.

Even last season, after the defense spiraled down the stretch -- giving up 553 yard and 47 points to Utah in the Pac-12 championship game and 539 yards and 46 points to Tulane in a listless Cotton Bowl performance -- Riley remained resolute that Grinch was his guy.

"I know what he's made of. I just do, and I just, I know it's getting ready to happen defensively," Riley told reporters in January. "I just have a confidence and a belief there."

Riley continued to emphatically endorse Grinch through the spring, fall camp, and some early season stumbles.

After an ugly win at Colorado in which the defense gave up 564 yards, 41 points and almost a second-half collapse, Riley was questioned why the defense with better talent and depth this year looked to still have all the same issues. He disagreed strongly.

“When something doesn’t go our way, it doesn’t look like last year. Not to the trained eye. Not to the coach," Riley said.

Sometime between Saturday night and Sunday morning, Riley saw what the untrained eyes had spotted long earlier -- it was time for change.

Riley had also said this back in January, though.

"I'm all for continuity. I think it's a good thing if you have the right people, but sometimes it doesn't work. Sometimes it's not the right combination of people, it's not the right setting or it just doesn't quite click in, and at that point, when that happens, then you have to make changes. I mean, that's the nature of this business. Nobody likes it and it's one of the ugly parts of it, but it's real. And I could promise you if I felt that way, then I would make changes."

He didn't feel that way then -- even though much of the fan base and many critics did -- but he backed up his words Sunday and will now enter the offseason looking for a new defensive coordinator and a new defensive identity on the Trojans' way into the Big Ten.