WATCH: USC DC Alex Grinch talks struggles, frustrations vs. Arizona

USC's defense is in a bit of tailspin the last two weeks, no doubt coinciding with some key injuries to middle linebacker Eric Gentry and fellow inside linebacker Ralen Goforth, but defensive coordinator Alex Grinch isn't making excuses.

And he doesn't want to hear excuses from his players either, like how close they were to making a play, or how Arizona's wide receivers made difficult one-handed catches on a multiple big plays Saturday.

Speaking after practice Wednesday, Grinch had a long diatribe on that particular notion.

"Close is a cancer, and a I mean that in a very dramatic sense," Grinch said. "You can kind of hold onto that and say 'We'll be closer next time, which means we'll inevitably make the play.' That's kind of been the story over the last two weeks in a lot of ways. Now, what that does mean is you're close, so does that mean dramatic adjustments, dramatic changes? No, we played man, we played zone, we rushed, we rushed five, we blitzed. ...

"But no, I think you also look at it through the lens of, rewind the tape. Everybody sees the one-handed catch, everyone sees the 'Oh, you almost got to the quarterback.' Let's rewind the tape to the snap and how do you get closer? What if you have better get-off? It's not always at the tail end. Well, he had a one-handed catch -- well, he had a one-handed catch because you opened up the gate and let him run a 40-yard dash on you and now he's not worried about you, he's worried about the football. So that's one of the kind of the mantras that we have -- we all saw the end result, how do we make up that ground. And sometimes it's a call -- make a better call -- so we look at that obviously also."

USC won that game at Arizona, 45-37, but the Trojans have had their two worst defensive performances over the last two games, yielding 562 yards and 43 points on the road at Utah and 543 yards and those 37 points on the road against the Wildcats.

Some of those "close" opportunities for the defense were Grinch's biggest frustrations, especially in regard to the inability to corral mobile Arizona quarterback Jayden de Laura.

"If the unblocked guy doesn't make the play, there's not a great defense in football," Grinch said. "And they're not going to make every play, especially on scrambling quarterbacks and stuff like that. Percentages are never going to be 100, but it can't be 100 on their side, and I think 14 times an unblocked guy [failed to make] a tackle. That's obviously an issue."

Watch Grinch's full comments after practice Wednesday: