The same thing is true of people who have worked with me or for me. I identify the difference was stick-to-it-ness. At this point in my career, I'll take a medium-bright person who is enthusiastic and dilligent over a really bright person who isn't. The former just gets more done and is easier to supervise or mentor.

Then think of a group. My experience is that groups achieve more if they're composed mostly of medium-bright and dilligent, with a scattering of really bright acting as a spark.

Further there's almost no amount of brains that can make up for bad attitude. For rule-breaking, yes; often it takes an iconoclastic outlook to make true breakthroughs - either academic or in instituting a new procedure/analysis. (I would like to hear of RL examples of brains being worth a whopping big amount of bad attitude.)