I think what drives people crazy is that he looked like more of a game breaking talent in his rookie season than he does now. His shot was electric, he was quick and agile, and he regularly deked guys out of their jockstrap 1 on 1.
Details-wise he is a vastly superior player now, but for whatever reason that electricity that he possessed early on is no longer present for the most part. His half-wall clapper seemingly misses about 90% of the time, his short-side wrister that used to nearly take off the goalie's ear is nowhere to be seen, all the small touches that used to make him look like genius now go into skates and result in turnovers.
I don't think he's washed or anything, but I think he's really struggled to maintain the offensive dominance while staying on top of the defensive details. It's like it's all one thing too many for his brain to process.