It's both. This is the old Nature vs Nurture argument: Nature (strength, size, speed) vs nurture (skill, scheme). A great player (Joe D, e.g.) with an average O-line coach would probably have a similar outcome to the season as an average player with a great O-line coach (Dante Scarnecchia). Realistically, we need to shoot for a coach and players that aren't necessarily great, but better than average. Good, perhaps. If we had good players on the O-line with a good coach to boot, well....milk my whistle. That would be outstanding!