@ Pho
Agree, it's tough trading for the 1 year rental. It takes some major courage and faith but I think the league is skewing in this mercenary free agent direction. It's just as risky and takes more years to go the home grown star route.
As for the list of stars, 1) I think you are underrating George, tho health was a concern with him as well and 2) It takes a collection (usually, Dirk, Wade, maybe others being the exception). Lebron didn't win a championship without his star sidekicks. Shaq needed Kobe. KG, Pierce and Allen never came close until they teamed up.
Ainge is a notorious trader and not a guy that sits around and waits for things to fall in his lap. Sure, he probably wants to build a long term contender but that's possible with the ages of AD and Kyrie and Hayward. I think he's a home run hitter and he has watched a lot of close pitches come across the plate. The count is full, If he doesn't take a swing at the Anthony Davis pitch to try and get that home run then.... at best he's gonna get a walk.