The Ringer's Kevin O'Connor with a ton of info on how this went down.
"Koby Altman may be the latest person to call himself Cleveland Cavaliers general manager—the fourth in the last 12 years since Dan Gilbert bought the team—but multiple sources have told me that the Cavs owner was the one calling the shots on the trade that sent Irving to Boston, and he’s the one dealing with the fallout. Gilbert’s dysfunctional ways are old news. Gilbert
himself joked during Altman’s introductory presser that his GMs have four-year presidential terms. “A state of organizational chaos is Gilbert’s M.O.,” one executive told me. “Gilbert thinks he’s the protagonist in the story of the Cavaliers, when, in reality, he’s the antagonist.”
"But the Celtics wouldn’t have sweetened the pot with the Nets pick
and Crowder if Thomas were 100 percent healthy, according to a source with knowledge of Boston’s thinking, nor could Cleveland have demanded such a package. Thomas’s injury was priced into the deal, in the sense that he didn’t have full value."
Gilbert’s fingerprints were all over the drama that’s unfolded over the past week. Thomas’s health is what held up the deal, but according to multiple league sources with knowledge of Cleveland’s thought process, the unprotected Nets pick and Crowder were the pieces that Cleveland valued the most—those were the assets that got the deal done, not Thomas. The perception of the trade was that the Cavaliers and Celtics swapped franchise point guards, but for the Cleveland front office (and its owner), Thomas was the icing, not the cake."
"Thomas’s incredible 2016–17 season ended in the Eastern Conference finals when he reaggravated a right femoral-acetabular impingement with a labral tear. Thomas initially hurt himself in March, when Karl-Anthony Towns fell on him in a game against the Timberwolves, and then continued to play until he “couldn't play anymore,”
as he told ESPN’s Adrian Wojnarowski in a Tuesday interview. He is still recovering from the injury, though he should be able to return at some point during the season. The question is when.
The answer certainly matters to some members of the Cavaliers organization, namely LeBron James and head coach Ty Lue. One league source with an understanding of Cleveland’s situation told me that as news spread throughout the organization that Thomas could miss time deep into the upcoming season, James and Lue cooled on the deal. According to the same source, both the Cavs’ franchise player and their head coach were apparently told by upper management that Thomas and Crowder were being brought in to help the team compete with the Warriors, now."
"Multiple sources told me that Gilbert is operating under the assumption that LeBron will opt out of his contract next summer and leave Cleveland. So Gilbert and Altman targeted Irving trade packages that set up the franchise for the post-LeBron era, rather than the instant-gratification deals they’ve made over the last three years (e.g., trading first-rounders for Channing Frye or Kyle Korver). A front-office executive from another team inquiring about Irving told me that knowing LeBron was staying in Cleveland would have changed what the Cavs asked for in return for Kyrie. Though a wide range of league sources believe LeBron is LeGone, it’s not certain. Regardless, Cleveland doesn’t want to be caught flat-footed. The variety of assets included in Boston’s Irving offer allowed Cleveland to be competitive in 2017–18 while preparing for life after LeBron. Cleveland might have considered Thomas the third-most valuable incoming asset, but the team still wanted a healthy version of him."
"Multiple sources with knowledge of Gilbert’s mind-set believe the Cavs owner cares deeply about how the deal will be seen today and in the future, both internally and across the league—Thomas’s health and a less enthusiastic James and Lue had Gilbert shook."
https://www.theringer.com/nba/2017/8/30/16230536/cavaliers-celtics-kyrie-irving-isaiah-thomas-trade