^?Random examples:
1. He demanded a trade from a championship team to get more of the spotlight;
2. He refused to talk with teammates for two days in the playoffs;
3. He "led" his team to a 4-23 record without Lebron;
4. He and Dion Waiters clashed, to the point of a rumored fight. Kyrie allegedly froze Waiters out of the offense;
5. He had "communication issues" with Davis Blatt;
6. He threatened not to re-sign in Cleveland unless they fired Mike Brown;
7. He pouts on the court, which has been noted repeatedly in the media. He skipped Fan Appreciation Night;
Just go back and read media from 2014, before Lebron got there. Kyrie was being savaged by media and other GMs for his immaturity. Byron Scott noted he "changed" (in a negative way) after he made his first All-Star game.
You could make similar accusations about Kobe Bryant - clashed with teammates, demanded trade, is generally considered an a$$hole, failed to carry his team when he wasn't surrounded by talent, only cared about himself. But he was also one of the greatest shooting guards of all time and won many huge games when he had a good team around him. He hit game winners and terrified opponents. Everyone respected him.
Ask around the league and you'll find NBA players universally respect Irving's game. KD himself said so on a Simmons podcast recently. Any talk on character is, frankly, irrelevant when you're talking about a gold medalist, NBA champion and the guy who hit the shot over MVP Steph Curry to sink a team that won 73 games. I want that guy on my team.
There's also some revisionist history around IT. His offensive performance last season was historic. His defensive performance was remarkably bad. He repeatedly made known he expects a max contract - typically players will at least say, "Yeah, I'll think about that when the time comes." He undermined Stevens' roster choices at times in the media. Love his game - but CBS and the Celtics empowered him to get to that point. He never gets there in most other systems. If we can make a 5'8" PG who can't defend and was drafted last into an All-NBA guy, surely we can get Kyrie to be an average defender.