It was always bound to come to a head at some point -- a perfect storm of long-swirling pent-up fan frustration toward defensive coordinator Alex Grinch and that defense having a bad day to further embolden the external discontent.

That storm touched down sometime last Saturday in Boulder, Colorado, as the Trojans gave up 27 second-half points and led lopsided lead turn into flashbacks of the Cotton Bowl collapse from last season.

USC did hold onto a 48-41 win and its flawless 5-0 record -- while dropping another spot in the AP poll this week to No. 9 -- but the flawed performance spiked anxiety about what will happen against the likes of Washington, Oregon and Notre Dame.

Or Arizona, which visits the Coliseum this week with a top-50 offense (No. 43, 428.8 yards per game) a year after testing the Trojans in a 45-37 USC win in Tucson, Arizona.

Another outcome was also inevitable this season, meanwhile -- it was only a matter of time before the weekly questions about the defense from reporters (let alone the much rawer reviews on social media) would take their toll on the Trojans in some way.

That also happened Saturday, as veteran safety Bryson Shaw gave an impassioned defense of his defensive coordinator while insisting the blame was not on Grinch at all but the players who aren't executing what he calls.

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"Coach Grinch, he's doing a great job. We're letting him down. That's point-blank, period, we're letting him down. I don't know what to tell ya'll, but as players we're letting him down," Shaw said after the game. "He's putting us in the right spots, we're not making plays, we're missing tackles, we're not doing our job, I'm not doing my job. We're letting him down. We're letting him down."

Shaw wasn't done yet ...

"I don't know what else to tell you than we've just got to fix it," he said a few questions later. "I have full faith in this defense. I know every player on this team has full faith in this defense. We love Coach Grinch. Coach Grinch puts us in the right spots, he's a great coordinator. There's no other coach we'd rather him. We love him. I mean, he's doing his job -- we're not doing ours as players. That's all there is to it."

Meanwhile, head coach Lincoln Riley gave a three-word matter-of-fact response when asked if he still had the same confidence that Grinch was the right coordinator to turn around USC's defense.

"Yes, I do," he said, while also disagreeing that defense resembles the one that ultimately undermined the team a year ago.

The Grinch storyline is going to remain for USC the rest of the way, though, unless what is presently the 102nd ranked defense in the FBS (404.4 yards per game) suddenly morphs into the upper-echelon unit the Trojans need to truly chase their championship goals this year.

With that said, here's an in-depth breakdown of what we learned, heard, saw, etc., from the Trojans in practice this week leading into the matchup with Arizona on Saturday night in the Coliseum.

The pointed and impassioned responses that came after the game Saturday gave way to more even-keeled, forward-looking comments as the questions about the defense persisted through the week.

Starting with Shaw, who declined to engage when asked about his strong statements from Saturday.

"I'm just focused on this week. I appreciate the question, but I'm just focused on Arizona and getting ready to roll for that," Shaw said Tuesday.

Said defensive tackle Kyon Barrs: "We're not really worried about Colorado. We're focused on this week. We just moved on."

As for the emphasis for the defense in practice this week, it remains clear that the Trojans -- from coaches to players -- believe in what they're doing on that side of the ball, and that this remains an execution problem and not schematic.

"Guys are in position, man. Everyone's just got to -- I think it's a mentality thing. I said that in pregame, we just got to finish, man," linebacker Mason Cobb said. "Guys [got lulled] to sleep a little bit. I mean, you could tell the difference from the first to second half -- we were more aggressive in the first half from top down. So just keeping our foot on the gas, that's it."

Cobb, meanwhile, did address Shaw's postgame comments about this being on the players.

"I mean, you can't say he's wrong. We're there, we're missing tackles -- that means we're in the right spots," he said.

Rush end Jamil Muhammad answered a handful of questions about what went wrong and how the Trojans are going about fixing it, and throughout he kept reiterating that it's mostly comes down to one thing.

"Just focus. It's funny how focus works because if you lose like an ounce of it, it makes a huge difference," Muhammad said. "... We accept the challenge of going into this week and seeking the challenge of finishing the game."

Grinch is available to reporters every Tuesday after practice and he gave his assessment of what went wrong in Boulder.

He said, despite Shaw's comments, that the onus is on he and coaches to make sure the players are able to execute as demanded. But it also sounded like he agreed with the general assessment.

"Yeah, individual plays and individual drives. I think to come up with one blanket statement would be inaccurate. It would be nice to be able to do that. I think it's a number of different things -- you've got to make sure if you're scoreboard watching and that affects your behavior on the field, that's a maturity issue," Grinch said. "... That's one of the messages -- we've got to make sure we fight, scratch and claw for 60 minutes. That tackle we made in the first quarter, we've got to go make it again in the fourth. The takeaway count, the sacks, the TFLs, and one of the other things we talk to the guys about -- I feel like I'm sharing too much now -- but you've got to add 's' to everything. It's not 'a' play. We made a play -- it's plays.

"The number of plays that you need to win a football game, once you get in that middle of the third quarter, and as well call it the championship round once you get to the fourth quarter, it's like a whole new game starts. And we have to gain a bigger appreciation for that. That's defensive football -- you don't get to punt, you don't get an opportunity to rest and hope the clock runs out and all that stuff. We've got to coach them through that. It's one thing to say it, it's another thing to demand it and get it out of the guys. I believe we can, I believe we will."

USC's team mantra across the board this year has been the "the longer we go, the better we get," meaning that the coaches have been trying since the offseason to impart a sense of urgency and priority on finishing games strongly. That has been an even more specific message for the defense, which is what is perhaps especially frustrating about the performance last weekend, as the Trojans gave up their most yards of the Riley/Grinch Era (564) with much of that coming in the second half.

"We’re fighting, scratching, clawing. Not hiding under our desk. Excited for another one this weekend," Grinch said.

Riley was asked Tuesday to expound on his postgame comments that the struggles for the defense this year aren't the same as last season and where he sees the differences or improvements.

"First off, we’ve been able to generate consistent pass rush from all levels of the defense. I think we’re better from a blitzing standpoint, from the linebacker position and we certainly have guys up front both outside and on the interior that can create havoc, that can get in the backfield, they can create tackles for loss, so that’s been a big difference," Riley said. "I think the second has been the run lanes. We’re a little bigger, thicker, stronger inside, so when things have popped this year, when we’ve given up a run, it’s just – it doesn’t look the same. It just doesn’t and it’s not been because people are just getting moved way off the ball or you have this gaping hole here. ... It’s just a sturdier front overall and I think those have been the biggest differences, honestly.

"I think we’ve busted less, we’ve played some stretches of ball this year that, frankly, I don’t know if we were capable of playing last year, to be honest, so we’ve gotta put it together, we can’t just do it, we can’t just dominate a good offense for two and a half quarters like we did the other day. We’ve gotta do it for four and that’s our expectation that we will."

To the point about the pass rush, USC ranks tied for 7th nationally and tops in the Pac-12 in averaging 3.8 sacks per game. The Trojans are tied for 2nd nationally in tackles for loss per game at 9.8.

Instead of relying on one dominant pass rush force as the Trojans did last year with national sack leader Tuli Tuipulotu (who stopped by USC practice this week), it's been spread out with eight different players notching sacks, led by Solomon Byrd (4.5), Jamil Muhammad (4.0) and Romello Height (3.0). A total of 18 Trojans have notched at least 1 tackle for loss, led again by Byrd (7.5) and Muhammad (7.0).

USC is averaging 23.6 pressures per game, per PFF, which is up significantly from 18.3 last season.

Riley emphasized two areas he wants to see immediate improvement after the struggles at Colorado.

"Finish tackles on the perimeters and keep the quarterback in the pocket," he said. "When we did that, we played high, high-level defense. When we didn’t do that, like most defenses, you’re going to get exposed. The pressure’s been great. You look at the national rankings, we’re the No. 1 team right now at pressuring quarterbacks. It’s a phenomenal place to be.

"But there were some times where we just were undisciplined and you can’t let guys get outside the pocket. Especially the quality of quarterback we’re going to play this week, the quality of quarterback we’re going to see the rest of the way, we can do a better job on that and still get the pressure and the hits and the sacks that have been a big part of us being 5-0 right now. So we’ve gotta do that and we’ve gotta finish tackles on the perimeter. I think that’s the name of the game. ... Most teams you play are pretty spread, there’s going to be space out there and we’ve obviously gotta do a better job tackling and limit some of those plays like we did in the first half the other day."