For the previous few years, I’ve been checking the accuracy fee of the ball-strike calls made by umpires, dividing the variety of right calls by the whole variety of takes. It’s a blunt method, however as a result of umpires make so many 1000’s of calls every year, it yields strong outcomes. On Tuesday, I pulled the numbers for the 2024 season, and I discovered one thing I didn’t anticipate: Accuracy goes down relatively than up. In each single season because the starting of the pitch monitoring period in 2008, umpires have gotten higher at calling balls and strikes in response to the Statcast strike zone. That is the primary time I’ve ever pulled the numbers and seen a decrease accuracy fee. Nonetheless, that is additionally the primary time I’ve checked the numbers this early within the season, and it seems umpires are likely to make higher calls because the season goes on. Since 2017, accuracy in March, April, and Might has been 0.19 proportion factors decrease than accuracy over the total season (although the distinction in 2023 was simply 0.03 proportion factors). Right here’s what that appears like in a graph.
You understand how at the start of each season, there are a pair blown calls throughout a nationally televised sport (or at the very least, calls that seemed to be improper in response to the on-screen strike zone), and sure folks begin complaining that umpires are horrible and so they’re getting worse? These folks at all times catch me off guard. I often overlook concerning the missed calls when the season ends, however these folks by some means handle to maintain their umpire anger at a excessive idle via everything of the offseason in order that the moment baseball returns, they’re able to shout concerning the umpires once more with none must ramp up. I don’t understand how they do it with out pulling an indirect, however in a way, these indignant individuals are proper. Regardless that the umpires are at all times getting higher yr after yr, they’re almost at all times extra correct towards the top of the season than at the start — a lot in order that when the season begins, they’re worse than they had been on the finish of the earlier season. For a month or two, the umpires actually have gotten worse. We frequently say early within the season that pitchers are forward of hitters. It seems they’re forward of umpires too.
For every season, I broke down the general accuracy in two-month increments, basically dividing the season into thirds. I additionally broke down the accuracy throughout spring coaching and the playoffs, though there are many elements that make these numbers suspect. Throughout spring coaching, the umpiring pool is way wider. Maybe extra importantly, there are far, far fewer tracked pitches throughout spring coaching, each as a result of the variety of video games is so small and since not each stadium is about up for Statcast. That leads to a a lot smaller, a lot much less dependable pattern. The playoffs are additionally a a lot smaller pattern, however they’re additionally, at the very least in concept, deciding on for higher umpires. Working the playoffs is seen as an honor and a reward for performing effectively within the common season. We should always anticipate accuracy to be at its lowest throughout spring coaching and highest through the playoffs.
Typically talking, the outcomes match our preconceptions. Spring coaching accuracy could be very low and it options the volatility that we’d anticipate from a small dataset. Umpires are additionally extra correct within the playoffs. The crimson line is March, April and Might, and as you may see, it’s almost at all times under all the things however the spring coaching line. Not solely do umpires begin getting higher in June, however they hold getting higher proper via the top of the season, which is why the sunshine blue line for August, September, and October is often above the yellow line for June and July. The pattern is slightly bit simpler to see if we focus simply on pitches within the shadow zone, the world that’s one baseball’s width from the sting of the zone on both aspect.
Within the graph above, the dotted line represents that season’s total accuracy on calls within the shadow zone. Every information level represents the variety of proportion factors above or under that yr’s common. Not solely do the calls get higher because the season goes on, there’s a particular hole between the primary two months and the remainder of the season. Umpires are decidedly worse in these first two months. Nonetheless, 2023 was an actual outlier. It was first time since 2008 that umpires had been extra correct at first of the season than the top.
With that, I wish to carry you again to 2024. Up to now this season, umpires have gotten 92.46% of calls proper, down from 92.81% in 2023 and simply two thousandths of a proportion level increased than in 2022. Primarily based on all the things I’ve proven you, we should always anticipate umpires to get higher over the remainder of the season. Nonetheless, the drop-off from final yr is noticeable. Accuracy over the primary two months of the season has solely fallen as soon as earlier than, from 2009 to 2010, when it dropped by 0.16 proportion factors. Up to now this season, accuracy has fallen by twice that quantity: 0.32 proportion factors. That’s a tiny change, on the order of 1 name per sport, however that doesn’t make it any much less actual. We’ll have to attend and see how the remainder of the season goes, however maybe this yr actually might find yourself being completely different. Or, if it follows the sample of the previous decade and a half, accuracy will quickly be in its manner up.
