Even few Trento players used to him and winners thanks to him (also important ones, like Lanza and Colaci apparently, plus Djuric) after a while had enough of him and were ready to leave the team. At the end Trento decide it was time to change Stoytchev, so imho that's a clear sign he is a 'difficult' coach for the players.
But, if only few months – and definitely decent results – were needed to broke to the relationship between him and the players that shows something is going wrong.
But what is the real problem? The vision of the game, too structured (and collective) and too less creative (and individualistic)?
The human relationship with the players? The fact he is more straight about what happens outside court?