For more than a century, baseball’s home plate umpires have called a ball or strike based on interpretation of a vague, loosely defined strike zone. These subjective calls decided at-bats, games, seasons and pennants — and, naturally, stirred endless debate. Now, for the first time, this season Major League Baseball is instituting a review system in which players can challenge a ball-strike call. Meaning: For the first time the strike zone will be defined and there will be a definitive answer