A question, statement, or event which
comes from left field or
comes out of left field is completely unexpected.
The question came out of left field, but Mary Ann wasn't really surprised. This letter sort of came out of left field. Compare with
left-field. Note: In baseball, left field is part of the outfield. A ball is said to come out of left field when the pitcher throws it in such a way that it seems to come out of nowhere.