Marcus does some great things in a basketball game, but he sometimes over estimates his abilities. That's okay when you have lower level talent on the floor. But when you have Hayward, Brown, and Tatum on the floor with you, you need to direct spacing and concentrate on getting them going first. Marcus you're not Kemba. Kemba creates spacing just because the ball is in his hands and he's so dangerous.
When one of that 4 gets injured it forces the Celtics to go deeper into that bench and players like Edwards, Williams, Wannamaker, Green, Semi are counted on more. That's not good for the Celtics, that group is too young and in some cases just not very talented.
The Cs need a veteran tweak or two, and not just at the center position.