Stand at home plate on a baseball field and look out. The far left corner of the grass is a long way off, and the fielder standing there is the one you are least likely to be watching. Two things follow from that one picture: a ball can arrive from there before you see it coming, and a person standing there is far away from everybody else.
可以想成你站在本壘往外看。左邊最遠的那塊草地離你很遠，守在那裡的人也是你最不會盯著看的人。這一個畫面長出兩件事：球從那裡飛過來，你往往來不及反應；而站在那裡的人，離其他所有人都很遠。棒球的用法是實景，另外兩個說法是把這個實景借去講人和事。