Watching the all-22 of Mazi right now and I don't get where the extreme consternation is coming from. Like yea, he didn't look great on some snaps and certainly didn't dominate but he wasn't so outlandishly bad that I'd be losing my mind for a first preseason game.
He played 32 snaps, 15 were passes, 17 runs, which went for a total of 121 yards although 80 of those came on two runs that were bounced all the way to the outside/C gap and had absolutely nothing to do with Mazi even if he wasn't amazing himself on his individual reps (he lost one of them to a combo/double team and won the other on a single block).
So aside from that you're at 41 yards on 15 rushes and he actually looked good on several of those reps.
Similar to Tyler early on last year the issue when he loses is that he isn't playing with technique, namely his pad level rises immediately and he's not timing his hands properly and using his length to his advantage. That nullifies his strength and results in him letting guys get into his chest and losing leverage, which he can recover against on a single block, but when that happens against a double/combo he loses balance and gets rooted out.
He was doubled on almost half the snaps he played (14) and by my very subjective count, he won 8 reps, lost 6 and was neutral on 16, neutral being that it was more or less a stalemate or a play design where he wasn't in a position to make an impact, i.e. a bootleg rollout to the opposite side or a play where he's cut at the knees immediately on a ball that's out in under 2 seconds.
He mainly struggled against doubles/combos, although he also flashed against them too (2nd quarter - 14:10, 8:22, 5:53, 4:03). Of course he didn't show much as a pass rusher aside from a bit of a bull rush here and there, but that's to be expected in his first preseason game given how raw he is there.
All in all, an uneven performance but it's a rookie's first preseason game and he flashed a bit here and there, which is about all you can expect at this point. The problem is that the flashes are subtle for a player like this, like if he's muddying up the spacing of a run play and helping stuff things up to a 2 yard gain instead of 4, that's exactly what you want but it's not something that pops off the screen or is especially satisfying to watch.
Anybody expecting him to be a dominant, or even good pass-rusher at this point is just setting themselves up for disappointment, he's a project in that regard although a high-ceiling one.