not with a bang but with a whimper

not with a bang but with a whimper

In an anti-climactic way. Typically used to describe the end of something. The phrase is taken from the last stanza of T.S. Eliot's poem "The Hollow Men": "This is the way the world ends / Not with a bang but a whimper." We all thought the championship was going to be a close game, but it ended up being a blowout, and the season ended not with a bang but with a whimper.
See also: bang, but, not, whimper
Farlex Dictionary of Idioms.

not with a bang but a whimper

LITERARY
If something happens not with a bang but a whimper, it is less effective or exciting than people expected or intended. The Cannes film festival approached its climax yesterday not with a bang but a whimper, as thousands of disappointed festival-goers left early. Note: You can also say that something happened with a bang and not a whimper to mean the opposite. Should the monarchy go, it would be with a memorable bang and not a whimper. Note: This is the last line of T.S. Eliot's poem `The Hollow Men' (1925): `This is the way the world ends Not with a bang but a whimper.'
See also: bang, but, not, whimper
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • not with a bang but a whimper
  • whimper
  • stanza
  • a thing of beauty is a joy forever
  • commit (something) to memory
  • commit to memory
  • name and shame
  • hollow out
  • at length
  • go out on a high note