KG's already shown the greatest decline during our championship year, before the knee spur. Now, with surgery/rest, he'll to back to his '08 level. And that's enough for this team.
As for PP, without a true personal trainer, he'll have the greatest decline because he needs to bang, down low, some more, to get to the line, the perimeter getting-in-one's-face technique isn't going to work over time, as the younger players are still a tad faster.
As for Ray Ray, well, as someone stated, he'll go the way of Miller with a steady decline till the age of 39. All and all, let's hope that no one goes the way of Drexler, who was clearly in decline after the the '96 season. And he was only 34 when it happened. What a shame.