It seems to me that Stevens is bent on going with the trendy, Golden State-style offense despite not having the ideal personnel for it.
Golden State has the following 3pt specialists:
Thompson: 45.4% (7 attempts per game)
Durant: 41.9% (6 apg)
Curry: 41.7% (10 apg)
For Boston, on the other hand, Horford and Tatum are shooting 43.4% and 43.1%, respectively—really good, but on only 3.3 and 3 attempts per game.
And the Celtics who take the most 3-pointers per game aren't nearly as good, generally speaking:
Irving: 6.7 attempts per game, 39.1%
Brown: 4.6, 37.7%
Smart: 4.6, 29.9%
Rozier: 4.5, 37.3%
Morris: 3.9, 35.8%
Smart's percentage is the only truly bad one in the bunch, but Morris and Rozier have been inconsistent, and Brown is good only at the corner 3s, really. So Boston's best 3pt shooters (Tatum and Horford) are taking the fewest among the regulars. Seems like those two should be taking more, and the others taking fewer.
Hayward's return will help in many ways, including the 3pt attack, but it seems to me that Boston doesn't really have the big guns GS has—which begs the questions: Why shoot so many 3s? Or at least, why is anyone not named Tatum, Horford, and maybe Kyrie taking so many 3s? Why aren't the Celtics attacking the paint more?
Of course, the Cs have never been much of a paint-attacking team during Stevens' tenure (other than IT and Kyrie), and they really never excelled at it during the Rivers era, either. There have been TONS of times in the last decade-plus when, while watching a Cs game, I thought, "Why don't you guys take it to the rim more?!?" You get more free throws, which are easier points; you get in the bonus quicker, which leads to more free throws; and you get the other team's key players in foul trouble more often and sooner.
I guess what I'm trying to say is that Boston's offense needs to be more dynamic, instead of so often just settling for 3s (contested or not).