Getty Images/Ringer illustration Which stars will change teams this summer? Which general manager faces the most perplexing decision? Our staff weighs in on those questions and more at the outset of a busy NBA offseason. Do you hear that? Listen closely. It's the thrum of the NBA offseason grinding into high gear. The South Beach sun is setting on the Celtics' championship celebration. The NBA draft is less than a week away, with free agency soon to follow. The Bulls already made a highly questionable trade. It's all happening, and the Ringer staff is here to help you prepare. Here are their answers to five of the biggest questions that will define the summer. Who will be the biggest star to change teams this summer? Howard Beck: Jimmy Butler will be traded. Rival executives have been buzzing about it for months, for all the obvious reasons. Butler is about to turn 35 (with a lot of hard miles and a lot of injuries), with one year left on his Heat contract, and is reportedly seeking a two-year, $113 million extension. If the Heat grant it, they'll have little to no flexibility to add another star. And they absolutely need one. Credit Butler for powering Miami to two Finals in five...