Throughout the 2012 season we will take a look at the accuracy of MLB umpires by comparing their ball/strike calls to PitchFX data. With every team now having completed at least one series, let's take a look at the numbers.
First up, let's see which umpires expanded their strike zones during Opening Weekend:
Ed Rapuano manned home plate duties in the Wednseday night MLB opener between the St. Louis Cardinals and the Miami Marlins. He seemed to be giving pitchers some help as 16 of the 94 pitches taken out of the strike zone by batters were called strikes. As a point of comparison, league average called strike rate on pitches out of the zone last season was 9.7%.
Again, Rapuano's expanded zone on Wednesday was a product of 16 erroneous strikes. Over the remainder of the season, he'll likely move closer to his average from last season (9.3%).
From the above graphic, you can see that Rapuano was favoring the outside strike for both lefties and righties. Five of those strikes came against Marlins batters, while eleven came against Cardinals hitters. It didn't seem to affect the defending champions too much as they still managed to win the game 4-1.
Next up, we'll take a look at missed strike calls within the PitchFX strike zone....