I think the answer is in the middle.

I think Leach is a really good coach with a good, not great offensive system that lacks versatility

Because he's an excellent manager/decision maker/culture setter with a good offensive system, we're going to get pretty good and consistent.

However, to really compete for the West, he'll need to make some adaptations in the run game. It's probably why he's always won, but never won his division or conference