Kyle is a very good basketball player. He is very smart. He has a lot of savy moves. He is long. In the D league he would dominate only "good" basketball players, which is 90% of the D league.
In the NBA, he is probably the most versatile 10th man. Without a strong outside shot, he is simply too slow to be anything more than that. His length will sometimes get you a steal or a deflection. He will sometimes play catch up on defense when a guy blows by him and get a block from behind. He is smart enough to not turn the ball over as he passes it to someone else because his ability to score against a legit NBA defender is limited.
Can he get better? Sure. He is young and still developing, yada yada. Maybe the most versatile 8th-9th guy. He will sometimes look very good against scrubs in garbage time. He will get feasted on against legit NBA talent.
There should be no shame in any of that. He is what he is. If he is a starter for the Spurs, the Spurs will be in trouble.