I always thought Zydrunas Ilgauskas to be one of the more "professional players." Quiet leader, reliable, and doesn't make excuses.
He has overcome constant pain in his feet, has had to deal with insomnia, and had to deal with the trauma of his wife giving birth to stillborn twins. Still goes out there and performs, though. You never hear anything bad about about him, and he never makes a food out of himself on/off the court.
Didn't know any of that. That's the kind of characteristics that come to mind when thinking professional: do your job, do it right, and whatever else happens remember you still have your job to do -and do it right-.
Don't have to be cocky or make a drama from things outside the job.