I think you may be onto something, but I think there are either 3 guys who have jobs where they're not evaluated, or they don't do well. I think it's a bit more than you assume though. I think it's more about a passion for doing well in all aspects, and putting forth the energy to come on here and seek and share information, just as those who are exceeds or exception in their job because they put forth the extra effort there.
Then you get beyond "passionate" into the obsession arena, and there is just a fine line between the two, which I think many of us have likely waivered back and forth on, myself included right now as I'm getting ready to make a trip WEST. Sometimes I catch myself spending more time playing on the computer, shooting my bow, etc, and not dedicating enough time to getting things done around the house or maybe not taking that extra couple minutes to explain the "WHOLE Physiology thing" to one of the nurses working for me who asks a question because I don't feel I have the energy to go into a 10minute drawn-out explanation. Sometimes I have that urge, and I'll overload them. Lately I leave them a little more hungry for answers and explanations....
I think for guys like TFox that say they've never had an evaluation, if you give yourself a "personal evaluation," you can very likely relate to this. Job satisfaction also plays a part, thats why Derek is just showing up and collecting a check!!!