By this point, Black Sabbath's inability to retain a lead singer long enough to reclaim their place among metal's leading bands had become something of a tragicomedy of errors.
Here's the rundown on '13,' Ozzy Osbourne's first full-length album with Black Sabbath in 35 years: It's not embarrassing in the least. In fact, it's pretty darn good and at times it's great. It's unfair to ask, and highly unlikely, that '13' will eve…