I'm on record saying that we have too few games to evaluate Mac and Zappe, and that Mac and Zappe have been asked to do different things against different teams, and though Mac looked fantastic the middle part of last year, Zappe hasn't had that opportunity yet.
That being said, I think there is a thing Zappe may have that Mac does not, and that is the ability to reset, compactly, get his mechanics right, and throw with a quick release.
It remains to be seen if Zappe can be accurate on long balls, and maybe that's something Mac has over him. But a couple of those plays made by Zappe yesterday might not be made by Mac at all. Doesn't mean he's going to be better than Mac. But there are things you see that make a difference