Once you get to the pros, they assume you know the basics and don't have the patience to coach you from ground up. Instead of gradually building a solid foundation, he was forced to work with what he knew and try to use it against grown, seasoned pro players 5 years older and wiser. It was a recipe for disaster and most of the blame falls on his parents. The shortcut to the pros might have netted him a early payday, but it may cost him the ability to earn millions more in the long run.
It wasn't until he got to Japan that he was able to receive personal attention from a reputable coach in Bob Hill (former Pacers coach). It was the first positive step he has taken in the journey, but it's going to take a lot more time and quality coaching to erase the bad habits from his game and to rebuild that confidence and self-awareness he so sorely needs. If the Warriors want to get the most of their raw Bigs (Tyler and now Ezeli), it would be of the utmost importance to hire the best big man coach money can buy.
It a recent interview with Rusty Simmons, he said,
"You know that perfect you, the one you see in your dreams?" Tyler said. "I realized that I've never seen myself that way in reality. I came in believing that I was already all-everything. Now I know that there are a lot of guys who are better than me. Once you start respecting the skill in this league, you start getting a lot better."
Sounds like he finally realizes that he's not as good as he thought he was. He's behind the curve now and it's up to Tyler to commit to the work ethic and mental toughness required to catch up to the rest of his peers.