I think this is a good debate.
I think it's silly for anyone to say that we're a better defensive team without Perkins (and I'm not accusing the OP of saying that). However, I think the better question to ask is just how much the loss of Perkins matters from a points perspective.
First off, Kendrick was averaging 26 mpg and 22 mpg for his career. So he's only playing a little over half of the game. So for the other half of the game, someone else is in the game at center and the Celtics are STILL the #1 defense in the league, even when he's healthy.
What does that tell us? It think that tells us that while he helps, a lot of the defense is predicated on the whole team playing well, especially the other 4 starters who are playing WAY more minutes.
And to go back to my first question, if we're only giving up 91 ppg or so without Perkins, how much (point wise) is he really mattering? One basket per game? Maybe two?
And to be honest, I think that's probably generous. But even if it was a 2-4 points swing, can't that be made up other ways? Can't Nenad Krstic get 2-4 more points than Kendrick could? Can't the same be said about Troy Murphy, who could outscore and outrebound Kendrick?
And for those who think that defense can't be made up through offensive production, how do you account for the fact that Doc has routinely opted for offense over defense at the end of games, first with Posey in '08, and now with BBD today?
This is not me trying to knock Kendrick. I love the guy and think he's one of the best post defenders in the league. However, I think there are other ways we can make up for his absence and I think we have the tools to do it.