Have you watched any of the Back To The Beginning?
The Sabbath set featured a seated Ozzy. They opened with Warpigs where Ozzy went slightly off time in the first verse but like a legend Bill Ward was able to keep the band on track.
Axl looked and sounded like a doofus.
The worst that I saw was the singer from Disturbed butcher Shot In The Dark (Ozzy, Ultimate Sin album) where he came in too early thus cutting Jake's opening riff completely! He was also pitchy, sharp, and flat at other times throughout the song. I remain sickened! WRONG DUDE for the song.