He’s right; football character trumps every other aspect involved. All the talent in the world means squat without the character to do what it takes to get the most out of it and it’s what separates those who make it and those who don’t; the bad teams from the good, the good from the great. The greatest strategists can incorporate schemes to beat the opponent, but it is wasted if players don’t have what’s necessary to apply them.
Every player in the league is athletically gifted enough to be there and there is a razor thin line between super bowl champ and worst team in the league when it comes to that aspect.
Football character applies to GMs, coaches, scouts, trainers, and everybody else in football ops as well.