Why Are Baseballs Round?

English: New York Yankees manager Casey Stengel in a 1949 issue of Baseball Digest. (Photo credit: Wikipedia)

It's to allow maximum capacity and less breakage when being filled by machine with a filling such as custard or jelly. A square baseball would break at the corners and so would a triangular baseball.

This naturally leads to the question why baseballs don't have a hole running through the middle. It is true that having a hole in the middle of the baseball would increase the surface area of the baseball and improve the texture when the baseball is fried. Perhaps not surprisingly, the reason for baseball's hesitance to adopt this commonsense innovation lies in baseball's endearing but sometimes infuriating adherence to tradition, to "the way we've always done it."

Also not surprisingly, some of the game's most original thinkers have been willing to take a stand on this controversial issue. 

As Casey Stengel said, "It's high time something was done for the pitchers. They put up the stands and take down fences to make more home runs and plague the pitchers. Let them put a hole in the baseball and help the pitchers make a living."