The Spain international, 24, was the first Blues player to voice his disappointment at Roberto Di Matteo's sacking - dubbing the Italian 'a legend' - but is pleased to welcome Benitez as his replacement.
Di Matteo was shown the door by Chelsea owner Roman Abramovich following a dismal 3-0 UEFA Champions League defeat to Juventus in Turin on Tuesday, and the club moved quickly to agree a deal with ex-Liverpool boss Benitez that runs until the end of the season.
Mata said: "Rafa Benitez is a great coach. He's got lots of experience and won a lot of trophies with Liverpool, taking them to a very high level. He knows the Premier League too.
"Di Matteo's sacking means things haven't been going well but we can't just blame it all on the Juventus game. We can't just focus on what happened recently.
"It was a really tough blow losing to Juventus. It was a sad night for all the players. We thought we could at least draw, if not win the game."
One of Benitez's first tasks will be revitalising the career of Fernando Torres, who excelled when the pair worked together at Anfield before the latter's £50m switch to west London in January of 2011.
Benitez previously said of the striker: "He's still trying very hard but I still think he'll improve. Can he get back to that level? I'm not sure but he can improve, especially if he can improve his confidence, he can get back to high levels."