Offense in Major League Baseball (MLB) has decreased substantially since 2006, often attributed to increased testing and punitive action for use of performance enhancing drugs. However, there has been concurrent policy change affecting behavior of other league agents that may have also affected game play. I therefore examine the effect of these agents, MLB umpires, on offensive production in baseball. Estimates reveal that a substantial portion of the offensive reduction from 2008 through 2014 can be attributed to changes in the size of the strike zone. Implications are further discussed in the context of firm production relevant outcomes as they relate to the labor force and supervisor performance expectations. (JEL J44, Z22, Z28, L25)