Just on to say I think this happened with a LOT of bands in the 80s--bands, that is, that had been around since the 60s or early 70s.
Not trying to start (or continue) a debate on the relative merits of different periods in the Yes canon...just saying it seems like many bands who had already been around +/- 2 decades by the time the 80s were in full swing stumbled a bit in the 80s...succumbed to fashion, MTV, production techniques ala gated drums and MIDI-interfaced everything...a lot of them resorted to getting their songs from teams instead of writing themselves...
Heart, Jefferson (Airplane) Starship, even the Stones and Springsteen did some work that, IMO, was just NOT them in order to follow on the coattails of new things that were emerging. Success (both artistically and critically) was mixed in a lot of cases.
This isn't a knock against 80s music. I think a lot of bands and artists who kicked off in the 80s were inventive and fresh and I like a lot of music from that era (including some of the 80s work of many of the older bands I mentioned from previous decades) but I always felt like a lot of the Old Guard Rockers were sort of wandering in the desert throughout some of that decade.
Punk had come along and thrown everyone for a loop, around '76: and then disco was suddenly dominating the charts. The 60s and early 70s bands that thought they were the vanguard of a new generation suddenly were made out to be dinosaurs and in danger of becoming irrelevant. I agree, they were scrambling to try and figure out how to stay afloat in the new era. Some did it well and others not so much. But Yes wasn't having someone else write their songs for them, except insofar as Trevor Horn (who had taken the lead singing role anyway when Jon Anderson left, and was effectively an alum member) continued to play an active role. I thought they probably did the best job of anyone adapting; Owner of a Lonely Heart and Leave It made sense to teens like myself cutting our teeth on New Wave music, but also didn't sound like anything else out there. They weren't just trying to bandwagon on the Pet Shop Boys or Duran Duran or anything.
It's YES alright, though I've read that it, among others, were all written, recorded and produced before hand as solo Trevor Rabin material. Plus Anderson was almost included as a courtesy, since Trevor sang all the leads himself in the original pre-Yes recordings. - though i may be misinformed. -- But, that aside, it is YES. Kinda.
I think it's exaggerated to say 90125 was all written and done before Anderson rejoined. Like I said (post #16), it was supposed to be a new project with Rabin as front man, and they started that way. But from what I read, it was more like it was stalling out midway along. Anderson didn't really write much for the album, but it didn't come together finally until they brought him in.