Having previously taken charge of Getafe and Mallorca, Swans boss Michael Laudrup used his extensive knowledge of La Liga to his advantage during the summer transfer window.
That led to moves to the Premier League for Pablo Hernandez, Michu and Jonathan de Guzman, all of whom have impressed early on this season.
And Mata, who joined the Blues from Valencia in 2011, has revealed that he is particularly close to Hernandez.
"Pablo is one of my best friends in football," he told Chelsea's official website.
"I was with him three years at Valencia and I was sharing my room with him for two years. We used to go on holiday together and we used to play golf together. He is a better golf player than me.
"As a football player he is a right winger, he has pace, he has quality and can cross and score goals. He used to play in the national team as well, when we were in the Confederations Cup three years ago.
"He asked me how it was playing in the Premier League and I said positive things about this, and about this country, and I think he is very happy here. He is enjoying his life in Wales and has Spanish friends there as well and he is learning English. I think it is a very good step for him in his life."
The 24-year-old also had kind words for forward Michu who, like him, graduated from Real Oviedo's academy as a young footballer.
|BLUES TO STUFF SWANS
|12/1||Chelsea are 12/1 with Bet365 to beat Swansea 3-1 on Saturday|
"So far he is doing very well at Swansea, he is scoring and is playing like a number 9. So he has settled down in the Premier League very well."
The midfielder went on to further discuss the Spanish influence on the Swansea squad, speaking of De Guzman, Angel Rangel and Chico Flores.
"Chico Flores is a central defender and I played with him in the Under-21 national team," he explained. "We played together in a play-off to be qualified for the European Championships and he has experience because he used to play in Italy as well.
"De Guzman used to play in Mallorca and when I played against him he was a very dynamic midfielder with the quality to play and to defend as well.
"Rangel has played for a long time at Swansea and knows this country very well and for me he is one of the most consistent full-backs in the league."
Finally, the Spain international praised former Real Madrid and Barcelona star Laudrup, who has enjoyed a solid start to life as a Premier League manager.
"Michael was one of the best European footballers in history and the way he used to play, he is trying to include it now in his teams," he stated.
"They like to play with the ball from the back and not with the long balls.
"Last season at Swansea they played well against us, they moved the ball so quickly and nearly won. They changed players, changed manager but they are doing more or less the same this season."