Mata worked under Benitez at Chelsea in the 2012-13 season, where the duo claimed the Europa League title and a safe passage into the Champions League.
Benitez succeeded Carlo Ancelotti to take the reins at the Santiago Bernabeu last month and Mata believes the former Valencia, Liverpool, Inter and Napoli coach has what it takes to revitalise a Madrid team who ended the season without a major domestic trophy after crashing out of the Champions League in the semi-finals to Juventus.
"I had him at Chelsea and we won the Europa League. It was a great campaign, my best in terms of statistics," Mata told Marca.
"Benitez knows how to get the most out of every player and get them performing to their best. Benitez was key for me."
The 27-year-old went on to say he hopes current team-mate David De Gea does not follow Benitez to the Spanish capital this summer.
"Lots of people ask me about De Gea. He's a friend and I want him to be happy.
"He's currently one of the best goalkeepers in the world. From a selfish point of view, I would want to have him in my team."