Conversation so far:
What was Michael Anthony (musician)'s role in Van Halen?
Anthony played bass on only three songs.
what caused his role to start diminishing?
As early as 1996, rumors periodically surfaced that Anthony had been fired from Van Halen, despite claims to the contrary.
Was he actually fired?
CANNOTANSWER.

Question: WHen did he leave the band?
Self-contained rewrite: When did Michael Anthony leave the band Van Halen?