baffle vs have bats in one's belfry

baffle

verb
  • To bewilder completely; to confuse or perplex. 

  • To struggle in vain. 

noun
  • An architectural feature designed to confuse enemies or make them vulnerable. 

  • A device used to dampen the effects of such things as sound, light, or fluid. Specifically, a baffle is a surface which is placed inside an open area to inhibit direct motion from one part to another, without preventing motion altogether. 

  • A lever for operating the throttle valve of a winding engine. 

have bats in one's belfry

verb
  • To be crazy or eccentric. 

How often have the words baffle and have bats in one's belfry occurred in a corpus of books? (source: Google Ngram Viewer )