Bands where a member leaves, and BOTH that member and the band become more successful as a result

Yeah I don't buy that re: Van Hagar. The whole thing about Roth taking seven records to sell what Hagar did in four... well, yeah. Hagar joined after VH's best-selling album ever. the thing about the Hagar albums hitting #1 is useless imo, only sales matter.

I thiiiiiiink Van Hagar made more $$$, if I recall Hagar's memoir "Red" correctly, but yeah, established brand.

There were a lot of factors at work re: Van Halen vs Van Hagar. Van Hagar were building on Van Halen's established rep, and the industry around them was changing, too - they'd started out a bar band, served a couple of years as an opening act, and only in their last few years (say, 1981-84) headlined. Meanwhile, rock shows were themselves getting bigger, so VH circa '85 was able to play stadiums rather than arenas, which wasn't an option for Roth-era VH until close to the end of their run.

On the flip side, think how much Hagar lost paying speeding tickets.

I guess Fairport Convention shedding members in 69 to begat solo Sandy Denny and Steeleye Span and a little later solo Richard Thompson doesn't count? Not sure how popular Fairport Convention remained at the time. Maybe it does though, could be when they were closest to being a popular band. Certainly meant a lot of great music came out. The Albion Band or whatever variation thereon was also great.

The Commodores only Grammy winning single "Nightshift" was released after the departure of Lionel Richie.

hard to argue that they were more successful overall after he left, considering that was their last hit and lionel became one of the biggest stars of the 80s

I know but I was listening to that song this morning and was like wow that was the only Grammy they won (& not for "Easy" nor "3x a Lady" nor "Lady" nor lol "Brick House" etc.)

it's a good song

Did we mention Massive Attack and Tricky?

A rare situation where two members of a band leave and both the original band, now a solo act, and the new one do better:

Black Dog / Plaid

Okkervil River and Shearwater are an interesting case. Shearwater was originally an Okkervil River side project for songs which didn't fit on their albums, and for which writing credits were more or less split between Will Sheff and Jonathan Meiburg. I think Meiburg became dissatisfied with this arrangement so he left OR and after that SW became more or less a Meiburg solo project. Since then Shearwater have become much more successful than they were before the split, although it's a moot point whether OR have also become more successful.