you're partially right. It was known he had the genetic condition that would require surgery on both knees when Portland drafted him, but he then tweeked a knee afterwords causing them to opt to get it out of the way immediately.
as others have relayed, the surgeries were corrective and not expected to affect his outstanding athleticism at all. It's also been reported that his rehab has been going great and he has been cleared by Docs to resume full basketball activities over a month ago.
I recall him being very long and athletic at Duke but didn't see him play at Memphis where he was the #1 option. I really don't know what to expect but his top shelf athleticism makes me very intrigued to see what he'll bring.