1
general::
Phrase(s): out in left field
Fig. offbeat; unusual and eccentric. (See also out of left field.) • Sally is a lot of fun, but she’s sort of out in left field. • What a strange idea. It’s really out in left field.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Also, out of left field. Eccentric, odd; also, mistaken. For example, The composer's use of dissonance in this symphony is way out in left field, or His answer was out of left field; he was totally wrong. This idiom refers to baseball's left field but the precise allusion is disputed. Among the theories proposed is that in some ballparks the left field wall is farther from the batter than the wall in right field. Another is that in early ballparks, left field was often larger than right field and therefore was home to more lost balls and general confusion. [Mid-1900s] Also see FAR OUT.
American Heritage Idioms