The last thing the Celtics need is more injury prone players on their last legs, but with the money they'll have to spend you have to at least consider taking a low-cost flyer on a guy like Michael Redd (and make sure he isn't the primary backup option - meaning re-sign Delonte West).
What's the value of a soon-to-be 32-year-old shooting guard who has missed 185 games over the past three seasons, including 136 of 164 contests the last two campaigns? If you're the shooting-craving Celtics squad, you hope it's something low enough to be a potential bidder (whether that's the veteran minimum, the bi-annual exception, or a reasonable slice of the mid-level, depending on what lives on in the next collective bargaining agreement). Celtics coach Doc Rivers referenced Dallas' shooting abilities as a primary asset in topping the Miami Heat in this year's NBA Finals and has said that Boston needs to improve in that area next season.
I don't have any delusions that he's return to All Star form he know how to shoot the rock as well as anyone not named Ray Allen and I'm pretty sure he'd take a 1 year deal for a chance at a title, so why not?