The Baseball Economist: The Real Game Exposed by J.C. Bradbury Read Free Book Online Page B

inning).
    We also need to know how frequently runners are in a position to steal third base. Even if keeping a runner off third base is valuable, opportunities to steal the base happen infrequently. A player can steal third only when there is a runner on second with third base open. By adding up all of the event frequencies for a runner on second and runners on first and second, italicized in Table 3, stealing third is an option only 13.7 percent of the time.
    What we need to do with the information in these tables is to estimate the change in expected run-scoring from stealing third, which catchers try to prevent. A successful steal of third changes the game situation in three ways:
    • Going from a runner on second to a runner on third
    • Going from runners on first and second to runners on second and third
    • Going from runners on first and second to runners on first and third
    Since the change in the third state is rare—almost always the runner on first goes to second when the runner on second goes to third—let’s exclude it from the analysis. Table 4 shows the change in expected
runs per inning from changes in the base/out situation for all out configurations, weighted for the frequency with which they occur. We can use this table to compare the expected runs gained by stealing third to the expected runs from staying on second. The final columns of the table show the expected raw gain in runs from stealing third and the gain weighted for the frequency of times the initial state occurs in a game. The bottom right corner of the table sums the runs gained on a per inning and per game basis. The numbers tell us how much stealing third is worth if a runner on second successfully steals third every time the opportunity arises. The result: on average, stealing third nets the team about 0.4 runs per game, which conversely means keeping a runner from stealing third base lowers the opposing team’s expected runs by that same amount. The difference is not huge, but it’s large enough to be relevant—about sixty-four runs a year. If you are having trouble thinking of this number as small or large, you can view it as we view a pitcher’s ERA difference of 0.4 earned runs per game. As a manager, would you have preference between pitchers with 3.01 and 3.41 ERAs? I would.
    However, this difference is actually very small, probably too small to be the only explanation for the bias against left-handed catchers. Four-tenths of a run is the amount of runs a team gains if it successfully steals third base every time a runner reaches second base with third base open. Teams don’t steal third base every time the opportunity exists. Failing to steal third is costly because the team gives up a runner on second and an out, which are both valuable inputs to run production. An extra out means fewer opportunities to push runners across the plate, and the forgone runner removes a player that was previously in “scoring position.” That is why steals of third base are rare. 18
    So the gains from keeping runners on second from stealing third are small, and this is where the advantage of the right-handed catcher is supposed to be. Even if we made the extreme assumption that runners successfully stole third every time they got the opportunity against lefty catchers, and righties always put them out, it would net the opposing team only 0.4 runs per game. Since we expect teams to steal less than this, the expected gains are less. 19
    However, why don’t teams put lefties behind the plate if the benefits from excluding them are so small? As George Stigler warned, simply claiming managers have just been making a mistake for so long isn’t the best path to understanding. So let’s dig a little deeper. While the benefits of using right-handed catchers are small, maybe the costs will yield some answers. What is the cost of excluding left-handers from catching?

The Cost of Southpaw Bias
    A large benefit of playing a left-hander in the field