It is a moot issue as one of them is in the NBA DL. So the Celtics are trying to develop Melo and he is a work in progress who has had bad games and good games but has hardly been dominant in the NBA DL.
He is second in the league in blocks at 3.6 BPG. He is 48 in RPG. He doesn't even register top 60 in scoring and is 37th in FG%.
The only thing consistent about him is in inconsistentcy.http://www.nba.com/dleague/playerfile/fab_melo/game_by_game_stats.html
He is not NBA ready if he was he would be here. Celtics want him to develop, he has a lot of potential. But he needs strength and to improve his hands. He has flashed some signs of doing very well and has a better ceiling than Collins.
I would rather have a serviceble vet in the playoffs though as Melo will get you maybe a block or two and some fouls. He doesn't have the respect to over come a star call being a NBA DL player.