This sounds like something a coworker would write. Unfortunately the individual was not actually a top performer—just convinced that he was. He would consistently say things that were objectively wrong (lot of math in our field... pretty easy to verify with certainty whether someone knows what he’s talking about), but the rest of us were polite enough not to point his misunderstandings out very often as he would freak out and throw a fit if we did. He was basically above average, convinced he was several standard deviations above everyone else, and more or less humored by everyone else so we could get work done instead of managing his ego outbursts all day.

Slightly above average and a generally sane, nice person will likely be beloved by all coworkers. Slightly above average with a complex... not really