The word “professionalism” is used in a few distinct ways that are notable in their opposition.
When we mean it as a compliment, we often shorten it in a chummy, American sort of way. We might say, “Don't worry. Susan will get the PowerPoint done on time—she's a pro!”
In contrast, “professionalism” is rarely used for any other reason than its negation. If the boss says, “Rupert, we need to discuss your professionalism,” it's never, ever good. In cases like that, we can be pretty sure the prefix “un” will appear at some point during the conversation.
If we all agree that we like professionalism, why do we so often use it negatively, and why do we avoid the full word when we use it positively?
Maybe it goes back to our rapidly changing workplace, where styles of dress, titles, and even where work gets done is no longer the way it used to be.
Maybe it's related to our extreme specialization. We may not even know what professionalism means for the person working next to us, but we're pretty sure we can spot it when it doesn't happen, like when work grinds to a halt, when somebody drops the ball, when a customer complains. So we use the diminutive “pro” to make friends with those we don't understand and “professionalism” with those we know are screwing up.
But maybe there's something deeper suggested by the professionalism disconnect: that we have lost empathy for the difficulty of the work those around us are expected to do.