12. Al Horford - Illegal screens
Asking Al Horford to improve on anything at this point in his career is crazy. He is the player he’s going to be forever, but maybe he can learn to game the system even more.
Bam Adebayo has become the master of setting illegal screens without getting them called, so perhaps Horford could take a page out of his book.
13. Kristaps Porzingis - Perimeter defense
Just like Luke Kornet, Kristaps Porzingis should be looking to improve his perimeter defense this year, as he’s already an impressive player in almost every other area of the game.
Porzingis’ defense down low has become crucial for the Celtics, but he could still look to work on his ability to keep up with guys at the three-point line. It’s tough to ask an oft-injured big man to work on his quickness and agility, but that’s where he’s at.
14. Jrue Holiday - Right-hand finishing
Similarly to Horford, it’s tough to ask Jrue Holiday to improve on anything this late in his career, but if there was anything that could be nit-picked, it would be his right-hand finishing.
For whatever reason, Holiday loves finishing with his left hand, to the point where it’s a well-known preference. He’s a fine finisher with his right, but he should try to keep defenses on their toes.