Professionalism is the competence or skill expected of a professional. A professional is a person engaged in a specific activity as one's main paid occupation. An athlete is or should be proficient in sports and other forms of physical activity. So, at the end of the day, professional athletes get paid to play and are expected to do so, at the very least, on a more consistent basis than that of … non-professional athletes. However, most "professional" athletes do not play consistently and should be held accountable accordingly.
Being a professional athlete is or should be the highest level of athleticism possible, but that's not the case, because pro-athletes are always rated on the "what have you done for me lately?" theory, per-say, or the last time they had a chance to do something, what did they do? So they are constantly being rated and everything that they do, fail or succeed, is accounted for. Which would explain why there are professional stars and professionals that are not "stars". And of course, the stars are the more consistent athletes in their particular field and obviously, they take their jobs more serious than the average pro-athlete.
Though, I've played on many different non-professional teams of many different sports, I have never had the opportunity to play on a professional team, but there was always an implied expectation of everyone on the team, and if a player could not live up to that expectation, then change was very necessary, because nobody wants to lose, professional, nor non-professional, recreational or any other level of play. Sometimes, no … a lot of times, I watch professional sports and I don't understand how these professional teams tolerate when these paid professional athletes don't play up to their expectation. When we watch sports being played on TV, we expect to see how the sport should be played at it's best, kind of like the example of perfection.
If a sales person doesn't close the sale, then they don't get paid. Most doctors and lawyers only get one chance to foul up a patient or a case, then their career is, at least, seriously tainted, therefore effecting their income. A mechanic that can't fix a flat tire is not going to make any money. None of those professions are compensated nearly as much as pro-athletes, but are held to much higher standards. Yet, somehow, a pro-athlete can drop a game-winning touchdown pass and not only keep his job, but also maintain his income while laughing and joking about how he disappointed his team and his fans. How is that? Anybody can do that. A professional baseball player that hasn't gotten a hit in his last 15 games is still able to keep his job and his income is not effected at all. How is that? Anybody can NOT perform. Anybody can NOT live to up to the task. So, why are they still on the team and why are they still getting paid? I don't understand. If I was the coach / owner I would be highly upset and change would definitely be necessary.
Most professional athletes take for granted the opportunity that they have been given. For every pro-athlete there are many more non-professional undiscovered athletes that could do the same job just as well, if not better. Professional sports tolerate way too much failure. There are professional teams that have never won a championship, yet they employ the same members of their staff for several years. Why do they continue to allow this to happen? Pro-athletes get paid a lot of money for doing basically nothing, enjoying their lives, playing in the backyard, and the least that they could do is take their "jobs" seriously and perform when it's their turn to perform and set the example that is expected of them, or be held accountable for not being up to the task.