Is it really an overreaction... ?
This is the obvious question or the core of this debate. It is an overreaction in my view when, after one bad loss, you see statements like, "Joe is braindead, he never make adjustments", "Spoelstra is totally out coaching him", and so on. Joe made adjustments and the team won a big game, but do you see any comments that Mazzulla outcoached Spoelstra?
The adjustment that I liked is you saw them getting easy baskets off backdoor cuts, taking advantage of how MIA was overplaying to the 3 point line. This is a simple adjustment, I learned the backdoor cut in probably 8th grade. But this made a big difference. Oh, and MIA shot only 32.1% from 3 and what do you know, we win easily. The other thing that was actually positive in this game is that we won in spite of shooting only 29.7% from 3 ourselves. We took 37 3PAs, that is still a lot (32 of which were open or wide open). MIA had 20 (of 28) open or wide open 3PA.
I think it is difficult to compare Spoelstra to Mazzulla. Spoelstra was an assistant in MIA for 11 years and has been the head coach for 16 years, all that time working under Pat Riley. Is all this MIA success more about Pat Riley or Spoelstra? Mazzulla was thrown into it right before the start of a season after the coach was fired. He is way ahead of schedule.
Whether Mazzulla is ahead of schedule or not, he is the current head coach of a title contending NBA team. With that comes certain expectations. Spoelstra coached a couple of titles very early in his head coaching career. At the time, he was criticized a lot, questioned a lot.
If you set aside the hyperbole around Mazzulla, it is fair to debate wither the Celtics would be better or more likely to win a title, if they had hired a veteran coach. That would not be overreacting. I don't know the answer to that, it is a hypothetical. It is possible, but I don't see the glaring flaws that other see. The same things were being debated before Spoelstra won his first title in 2012. Spoelstra was a "good enough" coach. I think Mazzulla is too.