Di Matteo was pleased with Mata's response to his break, which has seen him rack up four goals and four assists in his last four games.
"It was just common sense to give him a break and the way he's performing suggests that it was very welcome by his body and mind," Di Matteo said.
"Juan Mata is a very intelligent man and I talked to him about this idea, and he bought into it and he saw the benefits of it.
"Juan has really raised the bar again after this break.
"But if you look at how he played last season, he had a fantastic first season in the English Premier League."