Maybe 
A 1yr deal then yes i would say lets bring him back. I really cant see it happening though. The Roster is almost full and the glaring weakness is still at Center
1. Rondo
2. Dooling
3. Bradley
4. Allen
5. Daniels
6. Moore
7. Pierce
8. Green SF/PF
9. Pavlovic
10. Garnett
11. Bass
12. Johnson
13. O'Neal
14. Wilcox
15. ? < we still need a Center!
So if Posey was signed, Then someone will have to be waived
didn't they sign Greg Stiemsma?
Not fully guaranteed...which means, they will cut him if there is someone better.
I don't think Posey is that player though. Most likely, he will keep the seat warm until the day before his contract becomes fully guaranteed, and then they will cut him, to have an empty roster spot for the trade deadline and buyouts. Basically, he is this years Brandon Wallace.