Cardiff have twice smashed their transfer record in recent weeks, first for Danish striker Andreas Cornelius, then for Caulker.
"It was a hugely brave decision on the boy's part. The easy decision would have been to stay at Spurs, but maybe not being No 1 choice there tells you a lot about Steven looking at his own career and stepping away from one of the biggest clubs in English football. He's moved out of his comfort zone but I think he could be one of the great England centre-backs in years to come," said Mackay.
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