Cover your bases

Does anyone have an explanation for the phrase "cover your bases"

That's a sports thing. Some of the fans on Phrase Finder will have to explain because my knowledge of baseball is zero.

It is indeed a baseball term. Whether it has an earlier, independent origin I can't say. That being said... in every baseball situation, a defensive player is assigned to "cover" (i.e., be available to make a play by being near) a "base," one of four positions, arranged in a diamond shape, which an offensive player attempts to circumnavigate, counterclockwise. It is a fundamental error to be in the wrong place ... so, by extension, "cover your bases" means to make preparations thoroughly.