I saw Watt live with Glenn Hughes. I know he had good credentials from Julian Lennon and what have you, but in a trio format with Hughes he wasn't guitar hero/gunslinger enough. Glenn takes up a lot of space with his voice and his bass playing, if you are going to be a guitarist with him you cannot be a shrinking violet. I hate to say it, but Andrew lacked gravitas, authority and experience as a player - that's not a knock, he was in his early 20ies back then. Maybe if they had done more stuff like this
it would have worked, but in a pure hard rock trio format, Andrew was back then still out of his depth.
His production work on Ozzy's Patient No 9 and Ordinary Man was excellent though. I'm sure he is a musical talent.