He told arsenal.com: "He's different [to Messi at that age] and I think he's more.
"If you have to look for a weakness in Messi you would say it is his ability to run without the ball, behind the defender.
"When he takes the ball to his feet he's like a Ferrari. But Theo is more a guy who has the timing to run off the ball and that is something that is difficult to find.
"We had Marc Overmars who was especially good at that and I'm a great, great lover of movement off the ball."