Context is everything.
Baseball - Bat .500 over 4 seasons - you're in the hall of fame.
Bowling - Knock down .500 of the pins in each frame of a bowling game you scored a 50. Not average.
Vocation - Score .500 on your CPA exam, you're a pizza delivery professor at the U of Yewts and not living your dream counting beans all day.
Basketball - Knock down .500 of your 3 point shots over 4 seasons, you're fantastic.
Basketball - Knock down .500 of your free throws over 4 seasons, you're a bum.
So .500 is just a number. In college head coaching context, .500 overall is NOT average. It's poor.