Ferguson's comments were made on Tuesday evening at the Citizens' Theatre in Glasgow, where he was the guest of honour at an 'An Audience With...' evening attended by family, friends and fans.
"He was never a problem until he got married. He used to go into work with the academy coaches at night time, he was a fantastic young lad," he is quoted by the Independent on Sunday.
"Getting married into that entertainment scene was a difficult thing - from that moment his life was never going to be the same. He is such a big celebrity, football is only a small part. The big part is his persona."