He's probably the most underperforming coach of all time when he has actual talent, but I watched him go 8-8 with Mason Rudolph and Duck Hodges also. He's a complete enigma of a coach, and it is why I wouldn't consider him an upper echelon coach. An upper echelon coach can get star players to buy in and win (Belichick, Reid, McVay). I don't agree with how Tomlin runs his coordinators, but I found the Flores hiring encouraging.
Overall, I'm not a Tomlin fan, but I also remember people running Jamie Dixon out of Pitt, and a lot of long time Pitt fans warning those fans that sometimes the devil you know is better than the devil you don't. I don't see guy out there who is a marked improvement on Tomlin. Some may say Flores, but Flores didn't have an easy ride in Miami and made some enemies.