The Celtics are very big already, with players usually on the floor that average an inch or more longer in height and (more importantly) wingspan across the board than their opponent. We heard every playoff opponent talk about it - "the Celtics are so long...."
Whenever it appeared they needed more muscle in the paint, like against Draymond Green, it was a mental issue, being pushed out of their game by a very wise veteran. If they try and play bully ball, they've fallen right into his trap, and will have stupid reactions like a 5th grader in the hallway upset about having his lunch money stolen and being humiliated. And Green is shorter and weighs less than every post player on the Celtics. He's barely bigger than Marcus Smart.
They have a 10 man rotation already, the point being to rest the regulars more than with the 8 man rotation that is the norm in the NBA. Anyone else signed at this point, including bigs, will only get significant playing time if/when someone is hurt, and in blowouts. There's a chance they can sign a developmental big to replace Horford but they'd be incredibly lucky to find someone that blossoms that much, because if that talent was obvious, they'd already have a huge contract somewhere. Thomas Bryant is about as close as they might get.
