Koshcheck is the better wrestler.
Sherk has an amazing shot, but isn't the better wrestler.
It would be the same to comparing Phil Baroni to a top ten pro boxer.
if the pro boxer decided to get into MMA him and Baroni might both be KO'ing guys but a top ten boxer would still win in a boxing match even if he couldn't beat Baroni in an MMA match.
There is more to Wrestling than a good double leg, just like there is more to boxing than a powerful
jab, cross, hook combination.
"Koscheck...4 time division 1 All American, and went 42-0 en route to winning a national championship."
without olympic credentials, that's about as good as you get.