Boateng: Middlesbrough axe hurt me
He told the club's official website: "Being on the bench against Sunderland did crack my confidence, which is normal.
"It is an adversity, it is a setback in my personal career. But I have been there time and time again and I have overcome it, so it's another battle on my hands to come back fighting.
"I am not going to hide. My character will speak for itself. If people write me off, fine - they will be the same people giving me compliments at the end of the year."