The only argument I can think of for leaving that spot open is cheapness. We don't win our 2008 championship without PJ Brown.
There is not PJ Brown available.
Carmelo might fit that description at this point.
I have no interest in Melo. I believe he would cause more problems than he would solve with his ego, bad defense & shot-happy ways. He is not what this team needs.
Ego explanation = Would Melo be happy playing like B Griffin where he doesn't play most of the time and gets the odd game when the team needs him? Melo was happy in a regular bench role which he wasn't a few years ago but I do not know how well he'd handle another demotion to not playing most of the time.
Why would Melo be in the Griffin role. There is clearly room for a guy to play in the 3 or 4 role on this team.
Melo is not as good as Grant Williams. I would play Hauser and Muscala ahead of Melo as well.
Grant is obviously a better defender than Melo, but there are times that Grant just disappears and fades away and doesn't trust his ability. There are games I'd play the Melo of last year over Grant. I have no idea of the Melo of last year still actually exists as a player, but he seemed to embrace his role coming off the bench in Portland and LA the last two seasons, and he played pretty well. A guy like that has a role on this team, and I'd absolutely play Melo over Hauser and Muscala. No question about it. He is a better player (again assuming he is basically who he was the last 2 seasons). Hauser got brutalized yesterday. -16 in 20 minutes. just 1 of 4, did manage 3 assists and 3 rebounds in the 20 minutes, but he is a poor defender. If he isn't hitting his shot, you can't play Hauser, there is just no one else who can play in that role on this team. Melo could.
I have no idea if Melo even wants to play (I don't think his name has come up at all), but I do think he if he did, he could help Boston on a regular basis. The man knows how to score and Boston quite simply needs that some time.