Hazard burnt out.
He's just turned 30 and already has played 700 career games.
Prior to joining Real his previous 11 seasons as a first team player he averages 35 league games a season and if you add in the extras of cups and international football it jumps up to 58 games a season. On top of that he played in the 2 most physical leagues for 11 seasons. PL for 7 and Ligue 1 for 4. Btw I've not his debut season. He was 16 but he went from barely playing 4 games to 35 games in his first full season the following year
Being overweight for pre season is on him but I think his body has decided to give up on him.
Gooney, Torres, Sanchez, Eriksen and now Hazard I call this a pattern. All players who started out at 16/17 playing non stop played a number of years in the PL and hitting a wall once they hit their supposed prime years. And unfortunately I see this happening to many others in the future too. Rashford for one.
We saw what happened to Real Ronaldo and Michael Owen injuries destroying their careers. And while I do think Dele Alli current demise is more about ego and enjoying the celebrity stimulus package. His levels of performance had dropped way before Jose had turned up. He's another player who started playing non stop pro football from 16.