There's plenty of time to make the adjustment, the current coach is the assistant, so I'm pretty sure he is very much aware of the system and he just need to implement it, we were impressed by Udoka's performance last season, but he made a big mistake, so he has to face the consequences.
Yes, he has been an assistant coach for the Celtics for about 3 years now. That means he knows the system and the personnel. But is his experience enough to make tough calls in crunch time? Because that is the most important part and that could make or break the Celtics this year.
I think they won't continue with Udoka because of this situation.
They did very well with Udoka last season, but this season they have to do without him.
My guess is the Boston Celtics are looking for a new coach right now.
They are not looking for a new coach, assistant coach Joe Mazzulla, very young coach for them. Big Al is even older than him and he is the same age as Danilo G. (who unfortunately is injured and can't play with the team).
And he had like 3-4 days to settle down as their new coach in this most difficult time. The team needs to heal first before they can really go one with the start of the new season which is just around the corner. So really hard for the players to digest and see them without the coach that brought them to the finals and almost win the NBA championship.
Fortunately, it is very early in the season so whatever they need to fix, they have the whole season to do it. And, if Mazulla will not change the system, they have less to worry because the players are already comfortable with the current system. And he is the assistant coach, I am sure he also knows the system very well. He just needs the full trust of the players so he can guide them in crucial moments. He have the whole regular season to secure the player's trust, especially the star players.