It is impossible to absolutely define “professionalism” when it comes to most athletes because it is such a nebulous concept that covers a stunning array of parts.
It is as simple as showing up to work on time; it is as complex as trying to meld one’s personality with a couple of dozen others in the living organism that is a team.
It is eating right and getting rest, ignoring the tugs and hazards and distractions that come with youth, wealth and fame; it figuring out the intricacies and tricks of the trade playing against smarter, seasoned veterans who have all been there and done that.