There is a post on KG in Celtics history, but I firmly believe he should not have his number retired in Boston. He just didn't play enough years in my mind. I expect him to have it retired, I just wouldn't do it personally.
I definitely understand this line of thinking, but out of curiosity, is there a certain threshold you have for number of years/championships?
If the C's won 2 titles with Garnett, but he still only played 6 years, would you retire it then?
If he played out '14 and '15 with the C's, would that be enough?
The C's need some kind of Monument Park like the Yankees have. The greats like Ruth, Gehrig, Mantle, etc. get their number retired, along with stars who defined the Yankees for a generation, whether they won a ring (Mariano Rivera, Jeter in a year) or not (Mattingly). Then you have the next tier down of guys, All-Stars who were key contributors, but not on the same level or with the same tenure as the other guys, there you have guys like Paul O'Neill (9 years, 4x All-Star, 4x champion) and Tino Martinez (7 years, 1x All-Star, 4x champion). Also you have a tier even higher than the number being retired, with actual monuments (of which the Yankees only have 5).
A set up like that would be perfect for the Celtics. Pierce gets his number retired, while Garnett and Ray Allen get a plaque. If they had this in the past, then maybe Bird, McHale, Parrish get their number retired, while DJ and Max get plaques. I can also see monuments to Walter Brown, Red, Cousy, Russell, Tommy, Havlicek, and Bird (though I believe all the Yankee monuments are posthumous so maybe just Walter Brown and Red for now).
I think a setup similar to the Yankees would be perfect for the C's.