The 29-year-old - who only recently came out of international retirement - has looked a man reborn for his national side during the World Cup and Cole has suggested it's because he gets more "rhythm" with Morocco.
Before Morocco's World Cup victory over Spain, Cole said: "He just looks like a happier player for Morocco. He's had a very difficult time at Chelsea and he hasn't had a rhythm to his game.
"The Premier League doesn't suit him. It's aggressive, up and down. Playing for Ajax he could hug the touchline and the team would very much play through the lines, give him the ball and he's got a lovely left-foot, comes inside and delivers the ball.
"But when we've watched him here [Qatar], he's playing with an intensity and a smile on his face. Ziyech is a talented boy but it's just not worked for him at Chelsea."