"The move to the Bundesliga was a year too early for him to handle," said McClaren, now boss at promotion-chasing Derby County. "He should have stayed at Twente for another 12 months, or at least six.
"I didn't want him to go, you never want to sell your best players, but the offer that came in was just too much for the club to turn down.
"Certainly the Luuk De Jong I had in two spells at Twente will do very well in the Premier League and he is a tough kid, a very willing worker, good in the air, strong and a proven goalscorer. He is a threat to any defence, no doubt about it, a proven targetman.
"His attitude was always first class, I never had any problems with him at all. He was a very good, clean-living professional who worked at his game very hard.
"Although he was a muscular player you would never say he was over-physical or ultra-aggressive, that wasn't his style at all. He could put his foot in where it hurts but he wasn't a dirty player by any stretch of the imagination. I can only say good things about him.
"He is talented and he loves scoring goals, so I think he will do very well, but he will be lacking in match fitness as he has been on the sidelines at Borussia. It just didn't work out for him there - that can happen - but that's not to say it won't work for him in England because his style is more suited to English football."
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