Di Matteo said: "I don't know why he's underrated by the fans - he's very rated by us in the group. It's the kind of position where you're a bit of an unsung hero, where you do the dirty work which isn't recognised all the time because the goalscorers and the creative players get that recognition.
"He's physically strong, breaks up the game and is getting better on the ball, setting the tempo of our team. We're happy to have him.
"He takes responsibility as well when receiving the ball under pressure. He should get more credit for it."