Koeman is struggling to arrest a major slide at Barca, with president Josep Maria Bartomeu having resigned and Lionel Messi submitting, before withdrawing, a transfer request.
"And again you see that Lionel Messi currently cannot or does not want to. What he showed against Atlético Madrid is really outrageous. He only does something when he has the ball and now Messi often does not do good things with the ball. He also loses possession in places where you should not lose possession.
"Then Messi starts to trudge and that is deadly for the team and deadly for the credibility of Koeman as long as he continues to play Messi.
"It is very difficult for him, Koeman is sitting on a volcano that is about to erupt. And that can sometimes cost him his head."