From Wikipedia....
Matt Lukin was the first Melvins bassist and a founding member of the band along with Buzz and Mike Dillard in 1983.
He left the band in 1987, when Buzz and Dale moved to San Francisco. He remained in Washingon state and formed Mudhoney with former members of Green River. Mudhoney is still together, but Matt left the band, his last show with them was on January 20, 2001 at Graceland in Seattle.
Maybe he wasn't even fired??? Could it be that if Mr. Lukin moved to the Bay area with Buzz and Dale maybe there wouldn't even be a bassist morgue??? One can only ponder the answers......