His foot went flat because his un-informed training staff insists on taping and/or bracing his ankle to the point that it can't move. Decreased ankle mobility=eventual knee injury. Non-contact injuries almost always are the result of asymmetries in the body and sub par training programs. I said it in the other thread, I'm surprised nobody in the league but PHX seems to take advantage of corrective strategies such as the Functional Movement Screen. Nothing magical about PHX's training staff, they just actually use up to date practices.
It's no coincidence his left knee exploded after dealing with left hip and ankle issues all season.
PHX works out and treats the entire body during an injury. They're super smart about it. They understand, which I'm surprised most medical staffs don't, that when you are injured, you tend to overcompensate with another part of your body which causes much more stress. So a simple sprained ankle can turn into hip problems or spinal issues.