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Should the Yankees worry about Aaron Judge’s plate discipline problem?

Judge’s recent struggles stem from a breakdown in plate discipline.

Detroit Tigers v New York Yankees Photo by Jim McIsaac/Getty Images

Aaron Judge has struggled in the second half. That much has been well documented. Heading into Wednesday night’s game, he owns a .175/.337/.363 batting line with five home runs across 96 plate appearances. That works out to an 80 wRC+, down considerably from his herculean 198 wRC+ prior to the All-Star break. It’s abundantly clear that his performance has cratered. Any cross section one takes backs that up. Judge’s numbers have fallen in each category.

When a player slumps across the board, it’s rare to find a single datapoint that stands out as surprising. Yet, as I scrolled through my twitter feed yesterday, I came across this tweet from Mike Mazzeo of the New York Daily News:

Those numbers proved worse than I thought. It was shocking. Yet at the same time, I found it easy to visualize these struggles. Reading that tweet conjured up images of Judge swinging underneath high fastballs and waving at sliders down and away. These initial observations lead one to question Judge’s plate discipline, yet is that actually the problem? Or is this just a case of errant speculation?

There exist two ways to approach this question. First, one can fully unpack Mazzeo’s tweet, beginning with fastballs. It makes sense to look at the way pitchers use their heaters against Judge. So far in the second half, 58% of the pitches he’s seen have been fastballs. That’s only slightly above the 56.4% he saw prior to the All-Star break. If there hasn’t been a change in the number of fastballs received, then perhaps location plays a role.

To make a determination, it proves useful to compare zone profiles. In the first half, pitchers aimed for the lowest portions of the zone. This makes sense given his height. What’s considered low for Judge might get called as a strike for another batter.

Credit: Baseball Savant

How does that compare to his second half breakdown, though?

Credit: Baseball Savant

Now this map is interesting because it dispels the idea that pitchers are elevating their fastballs against Judge. That just might be recency bias at work. This plot does show, however, that they’ve found a target they like. The weak spot for Judge appears down and away. That’s where he’s apt to chase. Pitchers are quick to adapt. If they get burned, they learn to avoid an area. If they find success, however, they zero in on a target. This holds true for the slider as well.

Credit: Baseball Savant

Opposing pitchers know they can aim for the outer spots of the zones. They can target low and away and rest assured that Judge will swing at it. They’ve practically abandoned pitching to other locations. That’s how much success they’re having. The numbers back it up, too.

Location tells only one part of the story, though. It gives an incomplete picture. To fully grasp Judge’s struggles, one has to look at his swing rates. During the second half, his O-Swing% — or the rate at which one swings outside of the strike zone -- grew notably. At the same time, his Z-Swing% — a batter’s propensity to swing at strikes —- fell precipitously.

Credit: FanGraphs

The above chart tells us that Judge is swinging at the fewest number of strikes to this point of the season. His 43.5% swing rate in the second half is almost identical to the 44.8% he mustered prior to the All-Star break. He’s not cutting at more or fewer total pitches. It’s the quality that changed. He’s experienced a complete breakdown in plate discipline over the second half.

Obviously this inability to lay off balls outside of the zone is problematic. It’s the driving force behind Judge’s slump. When extrapolated on to a larger scale, it’s safe to say these struggles contributed to the team-wide malaise in the second half. That said, there’s reason for optimism. Judge demonstrated that he’s among the game’s elite at making adjustments. He put that skill on display at every level, including the big leagues. This leads one to believe he can correct the problem with some time.

For now, the Yankees have to ride out Judge’s struggles at the plate. This includes his sudden lack of plate discipline. It hurts right now, but his level of play prior to the All-Star break illustrates his ability. Would anyone be surprised if Judge figured it out tomorrow and he went on another tear? It might be infuriating in the moment, but I’m confident in Judge’s ability to adapt and grow.