Coaching without talent can make you win but never compete for Super Bowls. Talent without coaching just gets people fired … first the coaches, then lesser players, then more vocal players, and finally the GM.
Talent has a shorter window. Running backs have like 3-7 years typically. QB's have 10-18 years typically. Coaches have 20+ years typically. Given where to start, I'd always take the Coach, provide him with what he needs (like a GM to get him the talent). Eventually, the coach will win some, get more talent and then challenge. Most coaches hate their talent acquirers, complain a lot and try to undercut their GM's until the Head Coach has all the power. But he's a great coach because he has devoted all of his time to coaching. Anyone who devotes all his time to coaching cannot possibly be a great talent acquirer. So supporting the coach, typically means brokering peace between someone who has time and ability picking players (GM/scouts) and helping the Head Coach realize that he cannot possibly devote the time needed to be good at it.
Head Coaches that are great keep succeeding, mostly by finding ways to utilize the talent they have. The talent pool in the NFL is pretty uniformly high. The difference between great rosters and bad rosters isn't nearly as stark as people think. That's why someone like Jim Harbaugh or Sean McVay can be an overnight success. It's the reason so many new teams get into the playoffs each year. It's also the reason why a Super Bowl participant like Denver or Atlanta can lose a few key players and plummet from the edge of greatness to utter mediocrity. But, if you have a good coach, he can make a huge difference, even without the best roster.
Don Shula won the most games in NFL history. I think he only had like 1 or 2 losing seasons EVER. How is it possible to be drafting towards the end of the draft every year yet keep winning? Good talent scouts? Maybe, we've definitely had some in our time. But more importantly, good coaches use who they have and find a way to hide/minimize their weaknesses and utilize/emphasize their strengths. It's about the music the orchestra makes … not who has the best tuba players.