Short answer: Garnett is the best 1-on-1 defender on the team by a large margin, followed after a gap by Perkins and possibly Sheed (if we get Sheed from mid-2000s), followed after a gap by Pierce and possibly Sheed (if we get Sheed from last year), followed by everyone else.
Long answer: In this thread, Garnett's 1-on-1 defense seems to be underestimated for 2 rather ironic reasons. 1) He's such a great team defender/anchor that people tend to sleep on his 1-on-1 D, and 2) people aren't recognizing just how much Garnett's team defense helps his teammates look like better 1-on-1 defenders.
Let me start with that 2nd point. With Garnett in the game, his help D makes his perimeter defenders look like All Stars because they are able to play really tight on their man (Pierce/Allen) or take a lot of chances for steals/deflections (Rondo) without worrying about their man beating them off the dribble. And if their man does drive, in most cases he's going to either have to pass or shoot a lower percentage shot in the paint due to the help. And the pick-and-roll is entirely blown up. That's why in the '08 playoffs the C's perimeter defenders were able to hold down LeBron and Kobe but in the '09 playoffs they were torched by guys like Gordon and Rose.
Now, back to the first point, Garnett's 1-on-1 D is often overlooked. For one, he tends to play his men a lot more straight up than his teammates (after all, he doesn't have a KG as a help defender). For two, when KG is on and locks up a player they are LOCKED UP. He doesn't get to do it every game partially BECAUSE he is relied upon so much for help D, but when he does it he simply removes elite offensive players from the game. For instance, in the Pierce/Perk examples mentioned earlier in the thread LeBron/Kobe in '08 still scored 25-30 ppg just on poorer efficiency while Howard still averaged 16 points on 55% FG...they were held down, but still contributed. On the other hand, here are some of the games that KG has turned in against the elite scoring PFs in the NBA JUST in the 2 years he has been in Boston.
3/17/08 Tim Duncan: Duncan scores only 4 points after the 1st quarter when Garnett is switched onto him after he got off to a fast start against Perk.
11/10/08 Chris Bosh: Bosh scores 9 points on 38% FG. He had entered game as 2nd leading scorer in NBA at 27 ppg on 54% FG.
1/25/09 Dirk Nowitzki: Dirk scores 6 points on 2-for-9 FG with 4 TOs in the 25 minutes he played against Garnett. In the 6 games directly before and the 3 games directly after this game, Dirk averaged 29.1 ppg.
When he's on KG doesn't just limit his opponents, he surgically removes them from games. I remember for the '08 season, Wyc said that KG was holding his 1-on-1 opponents to something absurd like 13% below their normal FG%. That's ridiculous.
This is no disrespect to Perk, Pierce, Sheed, or any other Celtic. But Garnett is the best 1-on-1 defender on the Celtics by a really big margin...he's very possibly the best 1-on-1 defender in the NBA.
