The Celtics let Semih go because he wasn't going to play in the playoffs, he's a rookie but more important, he's injured. I think I read somewhere he's also having to deal with health issues in his family. I would have liked that the Celtics simply shelved him and wait for next year, but with the O'Neals uncertainty, I guess Danny made the correct move, trying to get some extra help, but I still would like to see Semih back in green next year.
Troy could bring that help, but I don't buy that comparison with Sheed. He can shoot 3's better than Sheed, but he's not as good as Sheed in the post. Post defense and post offense rely on the O'Neals shoulders, so they better be ready at the end of the regular season.
I wasn't very high on Murphy, but since he became a Celtic, I'm rooting for him to show up as a 3-point threat and a good rebounder. That would be good insurance for BBD, and I'll be very happy if he can contribute with 5-10 minutes when he's needed.