Conversation so far:
What group of Frank Zappa's disbanded?
Frank Zappa and the Mothers of Invention disbanded in 1969.
When did The Mothers of Invention disband?
Frank Zappa and the Mothers of Invention disbanded in 1969.
What kind of music did The Mothers of Invention play?
Their sound mixed R&B, doo-wop, musique concrète, and experimental sound collages that captured the freak subculture of Los Angeles at that time.
Why did The Mothers of Invention break up?
Frank Zappa often cited financial strain as the main reason, but also commented on the band members' lack of sufficient effort.
Why were there financial problems for The Mothers of Invention ?
Their first records were vocally oriented, but Zappa wrote more instrumental jazz and classical oriented music for the band's concerts, which confused audiences.

Question: why did he think the band lacked effort?
Self-contained rewrite: Why did Frank Zappa think the memebers of the band The Mothers of Invention  lacked effort?