Randy and Bob had a special magic that Ozzy has never had since Randy's death on March 19th, 1982.
Bob had a great career with Richie Blackmore's Rainbow and Uriah Heep too.
I heard at an interview, that he turned down a gig with Dio, after Dio left Black Sabbath and thst would have ended any thing to do with Ozzy, had he joined Ronnie James Dio .