Why are some words pronounced as though their letters were reversed?
For example, why is bible pronounced “buy-bel” and not “bib-lee”, or Favre pronounced “far-vuh” and not “fav-rah”?
Bible is not pronounced with “reversed letters”: the e is silent. Words like rhythm, acre, centre, bible, bottle, little, button all simply have syllabic consonants. For example:
Those all have two syllables, and all without a vowel in the second syllable. The consonants are acting as the syllabic center, which makes them fundamentally vowel-behaving, normally called syllabic consonants.
If you are talking about why some people will (“mis‑”)pronounce words like cavalry as calvary, or for that matter croqueta as corqueta, please see metathesis.