Besides Orlando, the C's don't have that much to worry about being killed in the center position. The Finals could be different if they are fortunate to get that far.
However, the Celtics will end up being a 3rd seed.
I don't like the Perk trade. The only way this becomes a good trade is if he doesn't come back 100% for OKC. The Celtics are in WIN NOW mode so signing him or not resigning him at the end of the year makes no difference to me.