Pretty much every year since 2001 that Miami ran a 4-3 defense we were in the top 25 for total defense, regardless of the coordinator. Manny has been competent at his job, which on Rick's staff makes him look like Bill Belichick.
I think we can do better long term. I'd be ok if he was the HC to finish out the season though. Also Butch is getting up there in years, probably has 3-4 more left in him, I would be happy to see Manny as the HC at FIU (although he'll probably be able to land a gig at a lesser P5 school like Minnesota)
PJ Fleck will win enough to keep his job.