I have said it a million times on here. Name a big run-stuffing NT you want on the Cowboys, and I will show you a guy who took 3 to 4 seasons to get going.
Vea, Lawrence, Payne, Derrick Brown, Wilkins, and even Big Q were all really average as rookies. Not good, but not difference makers at all, and they didn't look like they justified a 1st round pick. They all needed time.
The key is that none of those guys straight-up sucked as rookies. Like deer in headlights, blocking dummy, game moving too fast kind of stuff. There was at least a floor of competence they could build their game on top of.
It's hard to tell where Mazi is at, because he's had like 40 snaps for the entire season, but he has not looked lost so far. He hasn't been good, but he hasn't been bad. For a 1st round NT, that is basically on schedule.