He was a reasonably high-profile prospect coming up with LAD, and he essentially 'failed' to deliver on a lot of the expectations heaped upon him (and when I say 'fail' I mean 'didn't become Rickey Henderson with a SS glove, and was probably reminded of that fact on a daily basis by the LA media'). He gets moved off his natural SS position in his last year with the Dodgers, then is traded to the Marlins, and proceeds to win a Gold Glove, Silver Slugger, AND a batting title--all while stealing around 60 bases a year.
He got popped for PED's in 2016, which is obviously not great, but it's not unreasonable to expect that the suspension played a big role in his diminished output there (having that kind of thing hanging over someone's head would play havoc with focus).
So, in summary, we've got a player who can deal with adversity, who can bounce back after humiliation, and who not only can deal with a position shift but who can then become The Best At His Position, at least for one year (2015).
I see no reason to be bearish on his chances to make a successful transition to CF--where MOST players with his speed end up, and end up thriving.