2. Tacko Fall.
I think Tacko makes the most sense. He is already in the system, and he’s a huge fan favorite in Boston.
Fall is a big target and can score easily. He has the IQ and knows where to be to maximize his talents. Fall could be used during pivotal defensive stands, averaging 3 blocks (per 36 minutes).
Fall does have some negatives, like being slow, and not being able to guard the perimeter consistently. Currently the center position is not the strongest position on the Celtics however Fall would be an upgrade over Vincent Poirier.