Date: 1977 - 1981
It wasn't Joe Torre's fault. Not entirely, anyway. The Mets of the late '70s and early '80s were a truly dismal team, and Torre had never managed before. But still, you'd think a future Hall-of-Fame manager could have done better than 100-plus games under .500 over five seasons. Or at least managed to get them over .500 once. Nope.