The number of Spaniards in the competition has fallen from 28 to 24 this season, but the level of summer recruits has impressed Mata.
The Chelsea man's international colleagues Jesus Navas, Alvaro Negredo and Roberto Soldado - a former Valencia team-mate - have all been brought in at huge expense.
And Mata told Sky Sports News: "Personally I'm very happy to see them here and to play against them every now and then.
"I think it's very good for the league because they are top players - they can score, they can assist and change the game.
"For me Soldado, Navas, Negredo are friends - more than team-mates or rivals - so I'm very happy to see them here. I wish them the best but not when they play against us."
Soldado and Mata spent the 2010/11 season together at Valencia, and the striker has hit the ground running at Tottenham with four goals in as many games.
"I really enjoyed playing with him at Valencia and in the national team," Mata said. "I think he's doing really well.
"Last season at Valencia he scored a lot of goals, and this season he's started really well, like Negredo (at Manchester City)."