Haywood fills the role of 4th big at this point. Dalembert is better than him, but not so much better that we should used our roster spot for him.
This team needs a tight 8 man rotation come playoff time, because barring injuries and situational matchups, those will be only players playing. I think we all agree Lebron, Love, Kyrie, Thompson and most likely Marion are locks for playoff minutes. Mozgov and hopefully Shumpert are in that mix. I think the only thing missing from that rotation is offense on the wing. We have Miller, Smith, Jones and Harris to choose from, but Allen would probably be the best option. As nice as it would be to have one more insurance big man, I don't think Dalembert would play any meaningful playoff basketball and I'm not optimistic that O'neal will come here.