We've seen every possible method succeed and fail. Are some people better at picking a person to take over as HC? Maybe, but I've never heard of that person..........have you? It's like the draft, even if you have the #1 overall pick there is always doubt until the person is doing the job.
The thing I see that makes me say that the HC is less important than the QB/GM/Owner is because the fail rate is higher. How many HC's in the NFL have more than 3 years on the job? Answer......
ELEVEN. Essentially only one third of the NFL. And that number will probably drop because Harbaugh may be on the way out in BAL.
We see guys win Coach of the Year awards then get fired 3 years later. We see one season turnarounds that turn back around into failed seasons all the time. Did those guys forget to coach correctly? Or is it something else.
IMO in many sports coaching is over rated. Like I've said about 80% of these guys are all the same thing. The other 20% are made up of guys who know what to do and how to do it and guys who stink at the job. So a majority of the time (IMO) it comes down to the guy picking the players. And I don't want a HC picking the players, it's seemingly never worked well or at least it's really rare that it works out.