Id say that Zakk needs high stimulus as a player to excel and hasn't had it since Sharon Ozbourne got him fired for claiming that "Ozzy sounds like Zakk"
Conversly Ozzy hasn't been worth 2 fucks since Zakk left either.
I'm first in line for tickets to the Zakk/Oz reunion tour.
You cant sit in a green room for hours and do your best stuff in a 20 second sound byte.