It all went downhill for him since then. He had talent but he wasn't smart at all and wouldn't listen to what we were telling him and he and his entourage thought they knew what was best for his career. Instead, he's now in Belgium after being deemed not good enough for even Milan.
He was the same since the age of 16.
He had 2 moves in his game: dribble past 5 players and shoot.
Or play a 1-2 with a central player and shoot.
In Dinamo Zagreb, I have caught the reactions of his teammates 100s of times when they would ask in a disbelief: wtf are you doing?
Aged 18, he already had a fight with Croatian journalists who dared to question his abilities on a youth NT Euros.
He scored a goal in the next game, turned to cameras and said: shut up journos (as if: who are you to question me)?
His fall is imo a combination:
1. Of an insane hype. All Croatian and some European papers were calling him the next Messi
2. Secondly, his father and him bought a hype and he started to believe that he is really a generational talent.
Due to that he wanted too much too soon, like being promoted to Barca A too soon, not wanting to play for smaller teams and he also got mad at an NT coach Kovac before Euros 2016 because he didn't call him into an Nt team for Euros.
Then, Halil refused to play for Croatian youth teams after that saying that he is too good for that level.
3. On top of all, he really has a low IQ.
4. And very weak physique.
All in all, he was never that good.
He had some nice skills and resemblance to Messi in a way how he runs with the ball and dribbles and fans and media overhyped him probably by 300-1000%.
A kid is a victim of a modern era of internet, youtube and social media where everything NEW is insanely overhyped.