Chelsea assistant boss Ray Wilkins believes Kaka had concerns about competing in the Premiership after deciding to join Real Madrid.
"Well once again Real Madrid are buying some wonderful gifted players, but you can only play with one ball though," Wilkins told Sky Sports.
"It will be an interesting season, I will watch with interest what happens there. Kaka made his decision. There is a language barrier if he came to London.
"We will add to our players for sure. And we will compete for the Premier League.
He added: "For a foreign player it is difficult to play in the Premier League, so are these players taking the comfortable route by opting to play for Real Madrid? I don't know, I'm just playing devil's advocate, but the Premier League is still the best in the world."