And he expects big things from the vastly-experienced Boateng, saying: "No-one guarantees you first-team football.
"The only thing that can guarantee you that is playing well week in, week out - and that is what I fully expect from George but he has to get past the players who are already in the team."
Boateng said in March that he would remain at Middlesbrough as long as he remained a first-team regular.
His agent Barry Silkman told BBC Sport: "He has a year left on his contract but he has been there for five or six years and given them good service.
"He played about 80% of the season but he just thinks that maybe it is the right time to move on.
"Middlesbrough recognise he has been a great professional and say they won't hold out for a king's ransom should he wish to leave and won't stand in his way."
Boateng joined Boro from Aston Villa for £5m in 2002.
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