You can't just replace band members though.
You can if you get the band leader (and/or songwriter) to agree the album would be better with replacements.
Exactly,
I'm not sure why any of us are even debating with someone like Chris who has extensive experience in a recording and live environment, especially pre-digital/pro tools and has first hand experience replacing drummers on albums, so the Terry Williams / Omar Hakim story regarding BIA is not a rare thing. In fact even as a kid I was always not convinced about the drumming, Actually I thought it was even perhaps programmed. I have mentioned this before on this forum but for example the drumming on Def Leppards 3rd album Pyromania to me always sounded programmed. It was too perfect... yet the revelation that Rick Allen didn't play on that album only came about a few years ago to many fans suprise. The irony is he played more on the albums after his accident...
There are loads of examples of ghost musicians so to speak on albums. Many of those musicians aren't even credited. Chris in fact I bet isn't allowed to list all the albums or songs he has worked on because it wasn't in the contract. Also out of respect. I could be wrong but i'm sure Chris can answer that.
An example I have is a band called Urge Overkill. A very popular underground grunge band in the early 90's under Steve Albini's stewardship... they used to play with the likes of Nirvana. They were more about the image than the music. Medallions, clothing, attitude. However when they went mainstream Albini got very annoyed and even would go on to admit that the band weren't great musicians. Fast forward to the rather delightful album Saturation, released in 1993, and that was critically acclaimed. An extremely polished effort unlike their previous releases which had a more dirty / grungy sound. However i've read various articles since that actually whilst the songs were written and sung by the band, a lot of the music was recorded by session musicians or the producer. Andy Kravitz, who was one of the producers on that album for example played most of Blackie Onnasis's drum parts (RIP.) Whilst the bass was down to Hugh Macdonald apparently (Bon Jovi) and in fact Chuck Treese played bass on the follow up album the excellent Exit The Dragon.
So the Illsley stat was not at all surprising. There will be hundreds of examples with regards to albums from the 80's / 90's but like Chris has mentioned these days you can correct mistakes so there isn't as much of a call for session musicians to replace part because you can just cut and paste or replace parts with programmed music. I loathe that sort of thing actually, and i'm quite critical of albums these days and the way they sound. Very generic, and you can't really get a sense of the recording studio, the ambience etc. Then again i'm a hypocrite as technology has allowed me to record my own material / albums... and IF I can't afford my drummer mate to record a session in a studio I can use programmed / sampled drum sounds. The average listener wouldn't be able to tell the difference but i'm sure most of you and Chris would!