"In most firms, the top 10% at a given level outperforms the bottom 10% at the level above them." This is a really key point. This dovetails with another fact

"In most firms, the top 10% at a given level outperforms the bottom 10% at the level above them." This is a really key point. This dovetails with another fact of corporate life: over time, the median performance of any level degrades to the worst performer at that level. "I deserve to be promoted to VP. Look at Joe the VP, I'm obviously better than he is." Any company that isn't regularly clearing out the bottom 10% is fooling itself about both its hiring competence and its management skills. Any employee who can't get judged to be in the upper 90% of any organization isn't nearly as good as he/she thinks.