The Daily Mail says the Italian is believed to feel that his playing squad is not equipped to play the brand of football he wants to play.
And there is anxiety within the squad that Sarri's instructions are too complicated. Some members of the squad feel they are overloaded with tactical information ahead of matches, leaving many of them baffled as to what their manager is asking.
It appears unlikely that Chelsea will give Sarri carte blanche in the transfer market this summer to make the signings he wants in order to see his style flourish.
But despite the club signing Jorginho and Gonzalo Higuain — who both worked with Sarri in Naples — the Italian has privately expressed worries that his squad are failing to grasp what he wants.