I understand they have to make those adjustments quickly, but that's what makes them so good. Saban gives terminology and keys for everything so that his defense can react quickly and correctly on a very consistent basis. He lays out for every circumstance where a defender's eyes should go depending on what develops in front of him. And you have to remember, all these match-ups schemes are built-in so that Saban can maintain a numbers advantage in the box (8 in the box vs 21, 7 vs 11 personnel, etc).
And this isn't very different than Meyer's offense. Meyer's offense is full of very simple offensive schemes like those listed above. But a CB drops in such a way, he opens his hips in this way, he stays square in this way, etc, all are keys to modify routes. If OSU doesn't pick up on those things quickly, then receivers are running in the same area, then they aren't putting themselves in a spot to get open, etc. It's really a lot the same on both sides.
So again, as I was saying, it's going to be about execution at the end of the day. Which team executes their assignments more consistently? That'll be the team that wins.
I do think, even with Jones getting #1 reps for all of bowl practice, that not having Barrett is a big disadvantage for OSU. Barrett was much better at making decisions, and OSU was much more capable of opening up the playbook and schemes for Barrett than for Jones. Go back and watch the game vs Wisconsin and you'll note that OSU essentially ran Split Zone PA 3 Verts about half-a-dozen times. Read the safeties, throw away from them, CB is over the top, adjust to come back, CB even, run the fade. Simple two-step scheme: Safeties, movement key, throw.
While more practice reps will allow a few more things for Jones, there is a reason Barrett was preferred, and it's because Jones struggles to make those reads. That will force OSU to lean on the run game still, and have simple pass concepts like the 3 Verts, like Mesh, like Pivot, China (smash), and Drive and Chase. I don't think OSU has a lot of room to try to confuse Bama with routes that require more extensive reads than that. They need to get the ball out of Jones's hands and they can't sit back and force him to read defenses. That's not a Meyer offense strength, and it's not a Jones strength. I think you have to take that into account when questioning the match-ups for OSU vs Bama, and the short/intermediate middle of the field against multiple zone teams that run extensive match-up zones is a scary place to attack for any inexperienced QB that has some issues with accuracy.