HCs are obviously super-important. The question is whether or not communications and process have evolved enough to make the in-game calls more of a team process than they used to be, where you're not relying on one single person as much as you used to have to. And I think that's probably the case. You can have people responsible for more information and have that information more readily available than you did before, and then the coach can rely on that information, discuss it quickly over the headset, and have that collective decision piped in to the QB or the defense in real time where, before, all that processing had to happen in one guy's head and had to be communicated via signals or on the sidelines. The faster the processing and the flow of information gets, the less it's dependent on any one person. That stands to reason, doesn't it?