I live in LA too. A colleague of mine is a avid USC alum. He has been upset for two years about Riley keeping Grinch employed. His take was Grinch alone was responsible for 4 losses per year. I haven't dove in enough to care about the data, he and his alum friends are ecstatic that Grinch is gone.
It will be interesting to see how USC fares next year. They return only 3 starters on O, and 4 on D. With all the departures they are going through a roster turnover akin to the Buffs, except they never had a 1-11 roster, perhaps the least talented in the P68. The whole thing is strange. For the O, two of the returners are Oline, which was thrashed the 2nd half of last season, thus except for 2 guys they are doing a remake like CU. However, their transfer outflow is a net negative on player numbers--rather than evening out. Therefore, they really have to lean on some younger players for any depth.
Seems SC's D recruiting was strong on paper: blue-chips/transfer BC's, however, so many waashed out--many back to the market. This occurred with the O, as well. I think something has to be off with the recruiting assessments and overall player development. In three years like 13 D players have left with either a 4* TP ranking, or a solid BC coming out of HS--washing out. SC gets 4-5* LB recruits, and others throughout their roster, however they tend to wash-out or move on. With only 4 guys returning on D, it will be interesting to see if Lynn can change around the fortunes of their D--could look like the Buff's growing pains last year? They leaned on transfers from UCLA and Ore State in the rebuild, but just bringing back 4 guys with any starting experience renders each position group basically new. We lost CM and O Cooper, but Prime had replacements already on campus. I think it is unanimous that Dline wise, CU improved size and talent wise. Jury is out on the LB's but we signed some.
It is easy just to blame Grinch. Grinch is an interesting one, certainly a flail at SC. Prior to SC, maybe 2nd year at OU, Grinch was a fairly big name as a HCing candidate carousel for a couple of years. No doubt, Grinch's D's struggled, however I wonder how much of this is Riley too. In the end, Riley is in charge of the entire roster and the coaching staff. Given they have turnover in every position group (DB's all new except 1 safety) what does say about the entire D-staff? All the BC departures, what does that say about recruiting?
My gut sense is that Riley is Uber focused on O, being the QB whisperer, and the O/QB putting up their huge numbers, perhaps, not the entire team. I would argue CU's trajectory last season was heavily influenced by the Stanford collapse. If CU "just took the air out of the ball" in the 2nd half running clock, they probably hold onto that game, and maybe win a few more. On the other hand, Riley did not seem to change much year to year.