I was a big Helton supporter and used to defend him when folks would criticize him. I believed he would get it figured out turn things around. But he never did. I hate criticizing the guy because he's a genuinely good person. Outside of his coaching, you won't find a single person at USC who has a negative thing to say about him.
Helton was kept for at least 2 years too long, imo. His first couple of seasons were nice because we needed an adult in charge after the frat boys Kiffin and Sark. Helton provided that.
His main problem was his HC experience was as a G5 HC and that's how he tried to run the program. End result was that recruiting dropped off and where we were pretty much always top 10 and usually top 5, we were classes in the 10's and 20's. Not terrible, but you can't compete for NC's like that.
So, we'd end up with winning records every season, but when we got into games vs. the programs that we have traditionally stood toe to toe with like Bama, tOSU, ND, etc. the talent and coaching gap was glaring and was getting worse, not better.
Also, when I say "a lot to fix", I mean in getting back to traditional USC standards. It's why Riley had to hit the portal so hard.
As for Grinch, I'm not holding last year against him. They could only fix one side of the ball at a time and they chose offense. From what I've read and heard, there's more talent on this years defense, so we'll see if they improve.