This year?  Perk.  KG has been considerably worse than he was 2 years ago on the defensive end, while I think Perk has been about the same, if not slightly better.  They really work well together though, which is where their real value is.

Perk has drastically grown as a defender this year particularly.

Last year his defensive contribution was visually exaggerated by a lot of blocks that came from Perk’s help defense from the weak side.

Perk is above average when defending on the ball in the post and has turned into a nightmare for any back to the basket opponent (see: Dwight Howard, Emeka Okafor.)

However, he still lacks the ability to contain opposing Centers who can knock down jump shots and spread the floor. Chris Kaman magnified this on Sunday night. KG has this ability to extend his defensive presence.

KG and Perk compliment each other almost perfectly. Where KG is regressing, on the ball post defense, Perk is progressing. Where Perk’s athleticism limits him, defending the mid range game, KG is still athletic enough to cover.

Their impact is codependent, which is a compliment to both. Perk has made great strides to compensate for KG’s slowing down and KG was the catalyst for Perk’s defensive improvement.

Kevin Garnett -- far superior anticipation + response in his team defense + superior versatility (at a high level) in his man-to-man defense.

agree 100%..tp

The fact that we're talking about this speaks volumes about Perk's improvement.

Different and equal at this point.  KG is an awesome rotator and communicator and guards his man great.  Perk protects the rim better and is more physical.  Both are great.

Wow, I am shocked there is this conversation.  Against certain very big bigs, Perk is a better match-up than KG but in any overall sense, KG is by far the more impactful defensive presence.  That is no knock on Perk, KG is just elite, even still.  You can only know this by watching the games.  There is no stat.  He will help here, clog a lane there, all the little things as well as the monster blocks and shut down 1 on 1.  And he loves it, even derives energy from it.

Perk can muscle a big (albeit with fouls), and he is a great in-lane help defender; everything you want from a big.  But he is not everywhere like Garnett is.

My biggest problem with KG this year (although he has gotten better lately) is that he has not completely adjusted to his loss of athleticism.  Especially early in the season, he was making the same gambles that he used to make, and get away with, by using his exception quickness and explosive athleticism to recover from.  However, this year, he has clearly lost a step, and he does not have the quick and explosive jumping ability he had two years ago to be able to basically be two places at once.  In the last month or so, he has started to understand that and stop gambling quite as much (not to mention, gaining a little more mobility back), but I think this has set him behind a bit this season.

I definitely agree on this point. Luckily KG is doing a solid job of adjusting to the effects of aging. Hopefully he'll continue to improve and gain back even more of his stamina and mobility.