Let's not kid ourselves -- whether or not the Celtics bring back the current core, there's no getting around the fact that this group's elite days, collectively, are over. Sure, there's a chance one of them will go somewhere else and contribute to another championship run. Kevin Garnett still has something left as a defender, jump-shooting big man and overall emotional catalyst. Ray Allen, if he gets healthy, can still be a 3-point threat and overall high-IQ contributor. Paul Pierce assuredly has some big 30-point nights and buzzer-beating game winners left.
But no matter how much Rajon Rondo improves, he can't make Allen and Pierce more effective defensively or Garnett more agile around the rim. Thinking they have the requisite reserves to march through another 82-game season and then put together 16 wins against the league's elite is simply not realistic. Even relieved of guarding LeBron James down the stretch, Pierce didn't have enough left to carry the offensive load. Garnett, once his size advantage was negated by the return of Chris Bosh, couldn't consistently finish around the rim. Allen did his usual best getting open, but he can't guard his position anymore against the league's best and his driving finishes are few and far between.
Their will didn't give in; their bodies did.