I know everyone loves Powe, I'm his big fan too. But since he's leaving, we need to address what actually will be missing on the court. Doc had emphasized the importance of Powe's low post abilities to our team before:

"Leon was our low post scorer. Paul was an easy guy to trap. We became an in-out team to an out team. A lot of our points in the paint came off drives rather than feeding the post. Look at Orlando. They are a pick-and-roll team and an in-and-out team. After a timeout is called you know Orlando is going to go down low and then back out. Leon would have allowed us to do that a lot more.

"Leon also would have been a big help on defense because he would have been able to cover Rashard Lewis. He has quick feet. It also would have been tough for Rashard to guard Leon. That was a big loss for us. I don't think people understood how much it would have helped. It would have helped Baby, too. I think that dynamic would have pushed both of them." 
http://www.eagletribune.com/pusports/local_story_158012533.html

KG has some inside-out game, but not really a low post force. Perkins has some post moves, but he has the problems to perform the inside-out. Rasheed (or Dice) will be a solid backup C-F for sure, but he won't contribute those post moves as Powe did. We need to add a low post threat to our depth, and I think that's why Mike Sweetney is here.

I guess Sweetney will be the focus in our summer league team. Ainge said Sweetney is "trying to overcome some things that happened in his personal life and he’s been working really hard over the last six or eight months, maybe longer than that, to try to get back in the NBA." How did he know that? It sounds like that Ainge has been tracing Sweetney for a long time, but Sweetney has been a "desaparecidos" for the past two years:

"In the two years since his contract expired, Sweetney has not been heard from. He signed with no other teams, not in the NBA or any other league, and has not had any reported workouts. He hasn't played in any summer league, hadn't tried to join the D-League, hadn't been heard from in any fluff pieces in any newspapers, or appeared anywhere at all. Last season, Sam Smith reported that not even the NBA Player's Association could get into contact with him.

The only reported Sweetney sighting in the two years hence was in a Boston Globe article that mentioned how Sweetney was in the crowd at Bulls (Magic actually) vs Celtics game 7 last month."
http://www.chicagonow.com/blogs/chicago-bulls-confidential/2009/07/question-is-michael-sweetney-dead-answer-no.html

The fact that Sweetney was in the crowd at Magic vs Celtics game 7 makes you think twice. Was he worked at Boston? How long did the Celtics trace his comeback preparation closely? When did the Celtics offer Sweetney a roster spot for the summer league? While other ex-NBA players declared their availability through newspapers (such as Antoine Walker) before the draft, Sweetney prepared his comeback with unusual silence. Maybe there are some stories behind the screen.

Is Jeffrey Wechsler still Sweetney's agent now? Wechsler brought his another client, Darius Miles, for us last summer. It didn't work for some reasons, but a 6-9 Small Forward is actually what we need. This year Ainge bring in another comeback kid. Wish Sweetney has some good games at summer league and make our roster of pre-season camp.

Sweetney had some condition problems before, and so did Perkins and Big Al. It seems that the Celtics are good at handling the condition issue for our young players. Hope it works for Sweetney too. When healthy, Sweetney can be a talented low post player.

Since Ainge was so confident to let his only reliable low post scorer go early this summer, he'd better have some ideas to fix that hole. If Sweetney is not the answer, well, maybe we'll see Pierce play low post again, as he did before.