I'm fine with any of the following three options:
1) Defensive minded big man with length. If P.J. retires, we're left with very little down low. I like Powe and Baby, but both are probably closer to 6-6 than 6-8.
2) Best available player. This really couldn't hurt, especially with things so up in the air in terms of free agency.
3) A project with big upside. This might not be terrible either, especially when you consider how desirable of a place Boston probably is for free agents. Sure we have holes, but most of them could be filled in the short term with free agent signings. What we can't fill via free agency is a young stud to begin to step in as the Big Three fade. Rolling the dice on a raw project with big upside could help bridge the gap from the Big Three era to the Rondo/blank/blank era.