I've been thinking about how the original Mothers had some really talented musicians in their own right, but despite each member bringing a distinctive sound, and sometimes contributing to songwriting and lyrics, they're often forgotten in the wake of Zappa himself, and even he downplayed their contributions.

For example, I read recently that Ray Collin's daughter (Ray had passed away recently, in the last few years, I believe) had said on Reddit that Ray always maintained that the majority of the lyrics on Absolutely Free were written by him and Roy Estrada. Somehow I don't really doubt it, because the tone is quite different from later Zappa lyrics, and even he admitted to turning to Ray after having no idea what to write for the melody to Duke of Prunes. I also feel that, from that point onwards, this was the lineup of the Mothers - and also other Zappa bands - which had some of the most recognizable singers/players, and developed the most in a very short time frame. It also helped that they performed during what I consider to largely be Zappa's compositional peak.

I also think that when Ian Underwood joined he brought crazy arranging skills from his classical training, which allowed Frank to start writing even more complex material. Ian stuck with Frank through a ton of other lineup changes, but eventually get fed up with perceived lack of credit/royalties and left. I still feel like whether or not an Underwood appears on an album (either Ian or Ruth) will be a good indicator of how strong the album will be in the overall discography. George Duke also was a player who  brought a ton of skill to the band, and I don't think Frank ever had as good an accompanist on the keys for his solos - either before or after. The Roxy band was also the last band (imo) that was looser musically, and had a bit more latitude in terms of performance and solos. I think the later bands were over-rehearsed, and tended to have way less freedom instrumentally - other than the rhythm section during all the endless guitar solos.

So do you think that some of the bandmembers got overlooked in terms of ability?

If Roy Estrada wrote "Brown Shoes Don't Make It"...

...actually that makes sense!