What I haven't heard is exactly what the Bucks are hoping to get, but reading between the lines, I think it has to do with either a more interesting prospect than the Heat can offer, or more control of their own first round picks moving forward.
What they want is a young star like Paolo Banchero, Jalen Johnson, or Deni Avdija ... but nobody is willing to offer them that.
They are going to have to take a lesser package. Either a platter of picks and role player youth or an established star like Jaylen who is older than they would like.
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If Giannis had of been healthier these last few years, there would be a much stronger market for him and MIL could have gotten what they wanted. But he hasn't been. And nobody is willing to give up a huge price for him.
Outside of maybe BOS, nobody is willing to give up an established player as a good as Jaylen Brown either. I don't see anyone else offering anything close to Jaylen.
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Houston is not interested in making an offer. They believe they have enough internal improvement coming with the return of VanVleet that it is not worth giving up Sengun or Amen. OKC and SAS are already title contenders without Giannis and have the youth to be that for the next 10 years. An old injury prone player like Giannis is not desireable enough to break that up. Unlucky with the Lakers that A Reaves is out of contract. DAL are committed to building around Cooper Flagg and have little else to offer outside of him (old vet in Kyrie not desirable). DEN have nothing to offer except maybe Jamal Murray (similar offer to Jaylen Brown, arguably lesser offer than Jaylen). Minnesota have nothing to offer. Only Randle and some unproven youth (T Shannon, Joan Beringer). GSW have nothing to offer. Only POR can make an interesting and Giannis is refusing to go there. That is the West out except for maybe the LA Clippers who have the #5 pick & Garland.
New York just won the title so they don't want to break up their team. Cleveland has decided to stick with Evan Mobley so they won't pursue Giannis. Duren is a FA for DET and outside of him they have nothing to offer MIL. IND already have a settled team they are happy with in Zubac & Siakam and an offensive system built around Haliburton. Everything fits. Giannis does not fit. Even if they were willing to deal Siakam, that is a lesser version of Jaylen. ORL, ATL, TOR all have younger PFs who are their franchise players who they do not want to part with for an older injury prone Giannis.
There is no market for him.