Peyton Manning is another QB who was good everywhere and with anyone, and his coaches didn't find nearly the success without him as they did with him.
You can take any good offensive coach and look at the QB's they've coached, and you'll find that they have tremendously different performances depending on who is under center. They are masters of tailoring the offense to their QB, but can't seem to figure it out when they don't have their guy. Here are some QB ratings of note, only going with QB's that have started at least one game under these coaches:
Reid with Mahomes, Smith, Vick, and McNabb - 93.5
Reid with anyone else - 74.6
Shanahan with Purdy or Garoppolo - 102.8
Shanahan with anyone else - 82.9
McDaniel with Tua - 105.1
McDaniel with anyone else - 72.2
Payton with Brees - 101.5
Payton with any other Saint - 89.3 (worth noting he had Winston at a 101.5)