The Spaniard, who now turns out with Monaco, was sidelined by the Italian coach while at Stamford Bridge.
Fabregas featured in only five Premier League games under Sarri, who took charge of the Blues during the 2018/19 campaign, before leaving for Ligue 1 in January.
“Sarri is a good coach but he has strong convictions on a tactical level. He is very superstitious and it’s difficult to make him change his mind,” the former Arsenal and Barcelona star told Tuttosport.
“For example, he always wanted us Chelsea players to train at 3pm. It was bad for players who have a family like myself. We would not be able to see our children for the whole day. They went to school in the morning and they would sleep when we returned home after the training session.
“One day we asked him to let us train in the morning. He said we had to train at 3pm because a professor in Pisa had proved it was the best time for the body. I only know that for any player, it’s important to spend time with his family.”
This, allied with his inability to play regularly, was too much for Fabregas.
“He wanted to play Jorginho who had joined Chelsea for €60 million (£54m), playing only League Cup or Europa League games was not enough for me, I’ve always been a starter and in the end I left Chelsea,” he said.
Fabregas is now fighting for regular game time at Monaco. He has played 10 Ligue 1 matches this season and has returned one goal and two assists, though in recent weeks he has struggled to start for Niko Kovac’s side.
Sarri, meanwhile, is currently out of work after leaving Juventus in the summer following a single campaign in Turin.