Teams will simply double team him. Leave Rondo and double Dwight. We will still be in same predicament. For that reason I don't think Boston Celtics will be as desirable to Dwight. A point-guard teams will never respect his jumper-shot. Unless of course Chris Paul somehow finds his way to Boston. Only then possibly Dwight comes to Boston.
That's the way it works if your team is coached by moron Van Gundy. Doc Rivers isn't going to just post up Dwight Howard while everyone stands there... They'll have ball movement, multiple pick and rolls.
Celtics don't need Chris Paul. Rondo and Dwight would work fine, especially with Pierce, Allen, Green, and KG spreading the floor.
Rondo can blow by any defender, if anyone helps than you have either Ray or Paul outside, KG at midrange, or Dwight under the rim cause he's allowed to stand there for the entire shot clock.