Earlier today Rob Neyer sent out this tweet about Joe West working the ALCS:

Among 50 umpires with at least 2500 ball-strike calls this season, #ALCS crew chief Joe West ranks dead last http://t.co/lAFusjZiNl

— Rob Neyer (@robneyer) October 9, 2014

If you follow the tweet to the chart on umpire accuracy, and go to page four, you’ll see called 2399 of 2859 pitches correctly, 83.91%. There are 89 umpires listed in the chart, meaning the 45th umpire is the median ump. That’s Larry Vanover, who comes in at 86.38 percent. So the question I want to ask is, was Joe West really just the median umpire having a bad year? That is, what evidence do we have that his calling is just due to a year of bad luck? He might have had a lot more close pitches than other umpires, for example.

So we can ask the question, “If West’s ability was equal to the median umpire, what is the probability of him getting no more than 2399 pitches out 2859 pitches correct?” The answer is 9.20E-05, or 0.000092. That’s very low.

Another way is to calculate the 95% confidence index. For West as the median umpire calling 2859 pitches, that would be 2433 to 2505 called correctly. West is well below the 95% confidence range, nearly three standard deviations from the mean.

So balls and strikes is not his strong suit. Does anyone have any data on how often Joe West calls were subject to instant replay challenge, and how often they were overturned? If those numbers are bad as well, it makes one wonder why is umpiring in the post season.