Zola worked as assistant manager to Sarri at Stamford Bridge last season prior to the 61-year-old's sacking and Frank Lampard's subsequent appointment.
Sarri arrived from Napoli with a reputation for his attacking football, but things soon turned sour at Chelsea and he lost the support of the dressing room.
Zola says the Blues' first-team stars grew tired of his compatriot's methods, telling beIN SPORTS: "At the beginning the players were very much behind everything that we were saying, they were brilliant.
"They were following everything, but then as the weeks passed due to the repetition and the amount of games they were playing, the players got tired and they also got bored in a way.
"But boring is part of our job. Sometimes you need to get bored but when you get bored you persist in what you're doing and you get better. I remember that when I was learning to play football, kicking a ball for example, I used to do it 300-400 times a day at least.
"There were moments when I got tired but I needed to do it repeatedly because if I wanted it to become a part of me, this was the process I needed to go through."