The actual scoring is pretty balanced. Yardage heavily favors passing. There still needs to be a stout running game to punch the ball in once on the opponent’s side of the field even if passing gets you into position.

1. The spread tends to balance off the defenders versus offensive players from 11 defenders vs 10 + the QB. Most defenses use 1 or 2 safeties to support cornerbacks and avoid 1 on 1 coverage or go to a zone scheme. It's the classic choose what you want to try and stop, and I'll exploit it.

2. The defense often chooses to use lighter and faster players to cover the wide-open field, and unless you're stocked with JOKs, you become vulnerable to being pushed around.

3. Alabama has had a succession of big and somewhat fast backs that take advantage of defenses against the spread. Saban can kill other teams by having superior passing games (mainly the WRs) and running games. I think it's more than what keeps the defenses honest, but what the defense allows him.

4. As you pointed out in your original post, a good offense requires players and schemes to stretch the defense and to gain chuncks on the ground.

4.

On touchdown drives in the playoffs, Alabama passed 68% of the time.

If I did the math on every game the last five years, I’m guessing that on TD drives when the game wasn’t a blowout, it would be roughly the same. When Alabama wants to score now, they pass the ball.