Celtic paid £2.5million to secure the services of the Dutch defender last week and McCormack can understand why he was a target for both sides of the Old Firm.
"It was just his composure that stood out. He's like Boumsong when he was at Rangers. When the ball comes up hell bring it on his chest and pass it. He never panics and he's a mixture of maybe Boumsong and Kyrgiakos."
"I saw him for a couple of months, played with him a few times and trained with him. He'll do really well for Celtic â€“ I have no doubts about that at all."