left field

noun4

1. •
   The part of a baseball field which is beyond the infield and to the left of a person standing on home plate and facing the pitcher.
2. •
   (figurative) An unexpected, bizarre, or unwatched source (especially in the phrases out of left field and from left field).

   • Some of her comments really came from left field. I have no idea what she was thinking.
3. •
   The defensive position in the outfield to the left.
4. •
   (figurative) An unusual or unexpected position, or a viewpoint held by very few others in contrast to the majority viewpoint (especially in the phrases out in left field and way out in left field)

   • Tonne is way out in left field if he thinks a voice writing machine will never be built or that there are no existing prototypes or work being done in this […] — 1960