First, I'm not excusing what Kwahi has done in any way. He should be with the team. But I can see his issues. I said a long time ago, even last year, that Kawhi is not happy with the way Pop coaches. He doesn't like Pop undercutting him. It's not just one thing. I think its a combination of a lot of things.
-Kawhi doesn't like being subbed out when he clearly his a groove. There have been countless times where Kawhi gets rolling and Pop will just pull him mid groove. He'll have 15 in the first qtr, then gets pulled and plays 5 minutes the rest of the half. Kawhi sees other coaches let their players go on those special nights where they are just in a great rhythm. There are rare, rare occasions where pop lets him go. Kwahi wants to play like that every night, like other superstars on the league are allowed to. Tim Tony and Manu all got their chance to shine early in their careers. They "allowed" Pop's the micromanaging later. Kawhi hasn't been the man for but one year. He wants his chance to shine and put his stamp on the league.
-He doesn't like Pop pulling the plug so early on games, ESPECIALLY THE PLAYOFFS. How many time have we all seen Pop waive the white flag to start the 4th quarter. We all hate it and we don't even play. I can only imagine how much Kawhi hates it. He's been with him for 7 years and I think he's just finally had enough. All those losses add up and do damage to your overall seating come playoff time.
-He hates how all the resting changes the outcome of games before they start. So many national games, someone is always sitting out. I think he's tired of Pop not putting the best team on the floor night after night and giving games away.
-He's done with PATFO holding on to all these old guys that keep taking roster spots, and guys that can't help the team but keep getting resigned for "loyalty" or whatever, even to the detriment of the team. A token guy is okay, but the Spurs constantly have their roster filled with these guys year after year. I mean, Manu AND Tony are still on the team in 2018 and STILL counted on as major parts of the roster. If that is going to happen, fine, they're Spurs legends, but then you bring old useless Pau back? Then you sign Patty to the big contract eating up lots of cap space? That's 4 roster spots being eaten up by so-so guys. That's too many. Manu is the exception, but he's 40 and can't bring it every night anymore. Plus, three of those guys can't help you beat the Warriors. You know, the team everyone is chasing.
Again, I'm not excusing Kawhi's behavior in any way, but I can see why he is frustrated and wants to get off the Spurs team as long as Pop is coaching and the front office keeps doing what they're doing.