"It has been an amazing series for Mo, he is a legend," Cook told BBC Radio Four's Today programme.
"He is kind of the glue in our team, he is the unsung hero in one sense.
"He came into the side a few years ago when I was captain as a guy who could balance the side and bowl a little bit of off-spin and now he is the leading wicket taker in the series.
"His runs in the first game at Lord's, he got 80-odd, he has batted from one to eight.
