Kroos left Bayern for Real after winning the World Cup with Germany.
Boateng said: "You could already see it at the World Cup: Toni is a footballer who is nearly perfect technically, both with his left foot and with his right. It is him who decides the speed of the play.
"He has developed a lot in recent years and now he plays for one of the biggest clubs in the world."
For the big stories and the banter follow us on Twitter: @tribalfootball