“When you try to control the game from the sideline, you don’t have the answer for everything that’s happening on the field,” Brady said.
This Shanny's biggest flaw. When his game plan works he rolls to an easy win. If it doesn't work due to the D countering it or a key injury he has no Plan-B and isn't very good at thinking on his feet. He also plays not to lose, sits on small leads and has poor clock management and doesn't seem to understand the emotional dymamics of a game thus the 4th quarter fades.
Shanny is a great play designer and great OC (IF things go according to plan) but not yet a good headcoach. A HC is not a glorified OC because the HC needs to monitor the pulse of the team, rally them when they are down or calm them when they are amped and teach them both on and off the field. The HC also needs to actually watch the game (O and D) and see who is beating who on the field to know where to attack in crunch time. As it is Shanny has his nose in the playbook trying to scheme his way to a SB win but that is not how it works.
In short, Shanny does not yet realize or can't accept that players win games, not the coach, usually via unscripted and unexpected plays that aren't on his play sheet. Apparently he is known to be stubborn, defensive and a my-way-or-the-highway type and his ego can't acknowledge this fact.