be in left field
be (out) in left field
To be or seem uncommon, unpopular, or otherwise strange. Well, that suggestion is certainly out in left field! How did you come up with that one? Sure, my aunt is really wacky and out in left field, but I love her!
be (way out/over) in left ˈfield(American English, informal) completely wrong; strange or unusual: He’s way out in left field if he thinks we’re going to support him on this.
This idiom refers to the left part of the field in baseball.