Mata is preparing for Saturday's Champions League final at Bayern Munich.
Mata said: "I always had confidence in myself but never expected to do this well in my first season, play a lot of games and to win the FA Cup.
"We still have to play in the Champions League final, so it could be very special.
"When you are new in a dressing room, in another country, it is important for people to help you; and the players have done that. That's why I had the capacity to adapt quickly."