This is very interesting. Makes you wonder how much of a role Zizic will have next year if he hasn't developed a 3 point shot. Of course, AJ gets decent burn, so maybe not as big a deal as Danny lays out. I think that is the major weakness of Ainge's claim: Why couldn't we find a better rebounder to take AJ's place in the starting lineup.
I see a lot of people make the claim that the Celtics are only interested in bigs that can shoot threes and that's why they don't acquire a "rebounder." It seems like a mischaracterization of what the team's philosophy is. It's not that they don't want a big who can't shoot threes so much as it is they don't want a big who's only skill is rebounding.
What Ainge is saying is that if all a player can do is rebound, he's most likely going to hurt the team overall.
A big doesn't need to be able to shoot threes, but he should be able to do one or two of the following other things: protect the rim/provide interior defense, pass, defend on the perimeter, switch on defense, defend the pick and roll, provide elite rim running.
Drummond is a good example of this. He's an elite rebounder, perhaps the best in the league, but that's all he can really do. He has no versatility. Before everyone started spreading the floor, being a really tall dude that could jump high was enough to make you a star, but that's really not the case anymore.
Lack of versatility is chasing a lot of guys out of the league. Roy Hibbert, who was the second most important player on a ECF team 3 years ago, is going to be gone in the next year or two because all he can do is stand near the basket and jump up in the air. He gets roasted in a pick and roll, can't shoot, can't really rim run, and can't defend out side of the restricted area.
We don't need one-dimensional guys. Stevens won't play them, so what's the point of acquiring them.