65% coaching, 35% talent.
The reason we tend to overstate talent is because the best coaches naturally gravitate towards environments where they can pull in better talent. So we assume its talent and we undervalue coaching. But history is full of examples of teams with comparable talent from one year to the next taking huge steps back simply because of coaching changes.
OSU: Tressel 12-1 in 2010 > Fickell 6-7 in 2011
Arkansas: Petrino 11-2 in 2011 > John L Smith 4-8 in 2012
Florida: Meyer > Muschamp (despite what anyone says, the Meyer left plenty of talent there, especially for the SEC East, which is not veyr good)
Minnesota: Glen Mason 6-6 in 2006 > Tim Brewster 1-11 in 2007
Nebraska: Frank Solich 10-3 in 2003 > Bill Callahan 5-6 in 2004
Michigan State: Nick Saban 10-2 in 1999 > Bobby Williams 5-6 in 2000
Michigan: Lloyd Carr 9-4 in 2007 > RichRod 3-9 in 2008
Illinois: Ron Zook 7-6 2011 > Tim Beckman 2-10 in 2012
Those are just the ones off the top of my head. And they're great examples because in each of those scenarios, the teams under the new coach were playing with essentially the same talent level as the previous coach. And you can say things like "scheme changes" when it comes to people like RichRod, but A) even with a scheme change, 3-9 is pitiful given that the B1G in 2008 was probably at its lowest point in history, and B) great coaches find ways to adapt to what they have on the roster... like Saban (who completely overhauled his offense last year because he didnt have his ideal QB, and still found a way to dominate the SEC), or Meyer, or Tressel (who contrary to popular belief, was very diverse with his offense based on his personnel)... or best of all, Bill O'Brien, who did so much with so little and fit all the pieces into his grand puzzle, he should rightfully be known as the MacGyver of coaches. Give him a baseball pitcher, two basketball players, half a rugby team, and a handful of shot-putters, and he'll give you an 8 win football team.