It’s also silly to ignore that his prior coach also suspended him for being a bonehead and it seemed to have little impact, or that some players don’t develop the way we hope they would have for a variety of reasons. Calhoun’s style didn’t work for everyone, and Hurley has said—in reference to Sid iirc—that sometimes the more physically gifted players get lazy and coast for periods, and that those players are frequently not a good match for his style.
I don’t discount the potential impact of good coaching, but at this point I’m not convinced that Jalen is a good match for that same reason, or that he has a strong enough constitution to have survived four years under Jim Calhoun.