In the games KG has missed this season, the Cs have struggled mightily on defense. As we all know KG won't be around forever, and no matter how different the team may be come next season, we need a bridge to continue the defensive identity that's fueled the success of this group over the last several years.
Enter old friend Tony Allen, an unrestricted free agent come 2013-2014. Underrated as a Celtic and marginally better-known around the league as a top-tier stopper since the 07-08 Championship and his time in Memphis, TA brings it better than most and like KG his will and energy on the defensive end seems to be contagious. It's pretty obvious that Bradley and Lee are phenomenal man-to-man backcourt defenders, but both are on the smaller size and therefore don't match up well against the bigger superstars (of which there are many) in the league. Moreover, to this point they haven't displayed the exuberant, vocal infectious sort of defensive intensity that Garnett or Allen does---through no fault of theirs, it's just not in the personalities we've seen from them so far.
We hope Jeff Green will evolve into a superstar-stopper, and the thought of a rotating defensive core of TA, Lee, Bradley, and Rondo to lead by example and carry out Doc's system through what may be some lean offensive years to come is pretty exciting, at least to me. The Cs offense wasn't what did it in 07-08---as many have noted lately, it was their unparalleled defensive intensity and execution that gave them such a large margin of error offensively. If TA comes at a reasonable price (and we know he loved his time in Boston), I don't see why we wouldn't make a move. Whatever else happens personell-wise, a defense with those 4/5 stoppers can set this team apart far into the future. Especially if a defensive-minded big man or two find their way to Boston anytime soon.