[madrox]

Taking your argument to its conclusion, if there's a bad manager, then the director is bad, then the VP is bad, all the way up to the CEO. A single bad employee means the CEO is bad. I think we can both agree that stretches the definition of bad so far as to be meaningless.

Personally, I've seen bad managers under good directors. It's complicated. Anyone can make a bad hiring decision. My point is that even if you are able to identity bad people under you, that identification process takes time. The higher you go in a hierarchy, the longer the time horizon you tend to be evaluated on. To say it should be obvious on a very short time horizon is disingenuous and only covers the most egregious cases.