I find it an overly simplistic take to say only a championship matters. That you can't judge how well Mazzulla is coaching now, that you can only judge after they do or don't win a championship. The coach is going to have a lot less to do with any championship winning than the players.
That said, isn't it getting harder and harder to knock Mazzulla's coaching? No, they have not won a championship, but what more do you want him to do? If you are actually trying to pay attention to the games, it is pretty clear that the team is responding to the coaching, they are bought in. That is the biggest thing by far. Also, the team is now starting to show that they can adjust their game plan on the fly.
We are a small team, or at least we play small. We play with 1 big and an extra guard. A team with that structure is going to take more 3s than if the team started 2 bigs. That team is also going to give up more ORebs. My complaint all season has been too many 3s. Now they are adjusting and taking it to the hoop more, getting fouled more. My only remaining complaint is opponents ORebs, and I guess turnovers, but you are going to have more TOs when you drive to the hoop more. Not sure how you can coach away turnovers. The players need to clean that up.
Another thing to keep in mind is that we started the season with 2 new starters. It takes some time for a unit to settle in and play at a championship level. To be able to play to differing offensive schemes, without turnovers. It often can take multiple seasons for a core team to really gel. You can see the evolution of this unit. They are still getting better, tighter, more integrated.