The only comparable issue you don't have with Kyrie is age.
He's a terrible defender. Arguments about who is worse are absurd -- for whom is a difference between 3 SDs and 2.5 SDs below the mean actually meaningful? Maybe hardcore statisticians?
He's small -- 6'3" is a stretch... he has a 6' wingspan (smaller than mine), and weighs 155 lbs (smaller than my mom).
He's inconsistent. Why, tarheelsxxiii? Well, because he's exceptionally talented, but due to his size, relies on exceptionally cute plays to score.
He has proven that he can make big shots. He has star quality. That's good. But, he hasn't proven that he can lead a team to wins. Hopefully he can.
He's more injury-prone than Gronkowski. He averages 62 games/year, with multiple seasons below 55, and plays hurt very often.
I'll get over it in a season or so, then root for the kid like most other Celtics. But I am disappointed that we didn't sell off significant assets for a two-way player that can have a greater impact on the game. And for me, nothing to follow will take away from IT's incredible run in Boston.