In-Zone, Out-of-Zone, Hot-Zone, Cold-Zone: Batter Contact Rates

Hitters, it turns out, are pitched to differently based on their strengths and weaknesses. For their part, pitchers can choose what to throw those hitters and in what order, all the while doing their best to put the baseball exactly where they intend to. Increasingly, pitchers are exploiting a fairly common weakness among hitters, by pitching outside of the strike zone. Some hitters exercise patience in response to these tactics, while others are simply adept at hitting pitches outside the zone. Players like Joey Votto and Vladimir Guerrero, in my mind at least, personify the former and latter virtues, respectively.

Given these fairly obvious phenomena, what follows offers a quick glance into how hitters were approached in relation to the strike zone in 2020, and how they fared in response.

On the surface, it does not appear as though pitchers have pitched more or less frequently in the strike zone based simply on a hitter in-zone contact rate. The scatterplot below depicts the weak positive relationship between hitters’ in-zone contact rates and the percentage of pitches they see inside the strike zone.

The figure above indicates that hitters who made more contact in the zone correspondingly saw a few more pitches in the zone, relatively speaking. Drawing conclusions from the above is likely misleading though, at least in part. This scatterplot does not account for any number of omitted variables that additionally contribute to how a batter is approached. Essentially, hitters who receive a great percentage of in-zone offerings possess other key qualities not featured above.

As the next scatterplot illustrates, there is in fact a relatively strong association between individual hitters’ abilities to hit pitches inside the zone as well as outside the zone. What that association implies is clear: if a hitter has a relatively strong (or weak) hit tool, that tool generally transcends the strike zone.

The second visualization above helps to better inform the first. Pitchers, very generally speaking, fill the strike zone more often against hitters who have good in-zone contact rates. They may do so in part given that those same hitters are more likely to connect on pitches outside the zone as well and thus cannot be relied upon to miss on out-of-zone offerings as much.

The correlation between in-zone and out-of-zone contact (0.65) isn’t overwhelmingly strong though. While all qualifying hitters in 2020 had higher contact rates on pitches inside the zone versus outside, the scatterplot above indicates that those rates were still fairly close in some cases or extremely far apart in others.

To follow up on that point, the following tables list some of those outliers. Below is a table listing the 2020 batters with the greatest disparity between in-zone contact and out-of-zone contact; these hitters occupy the space furthest south of the turquoise linear regression line in the scatterplot above.

Hunter Dozier, who leads this list, made contact in roughly 5 of every 6 pitches inside the strike zone versus just 1 of every 3 of pitches outside of the zone, representing the greatest discrepancy in 2020. Perhaps in response to this trend, Dozier was in just the 7th (6.90%) percentile in percentage of pitches he saw in-zone; to his credit though, Dozier posted a career high walk rate to offset his out-of-zone contact struggles.

Paul DeJong, Corey Seager, Miguel Sanó, and Clint Frazier all made contact on pitches inside the zone more than 40% more often than those outside of it. Despite these extreme discrepancies, the above hitters saw a lot of pitches inside the zone; outside of Dozier, Christian Yelich, and Miguel Cabrera, this entire list was part of at least the 20th percentile for In-Zone pitches (column 4).

On the other end of the spectrum are those players whose contact rates less starkly differ across balls and strikes. Below is a corresponding leaderboard.

Despite this group having closer contact percentages across in- and out-of-zone pitches, their in-zone contact didn’t suffer as a result. In fact, this group maintained a higher contact rate on in-zone pitches (81.7% vs. 80.0%) than the high-discrepancy hitters. Simply put, this group features some proficient hitters. Given this, pitchers haven’t quite determined what to do with them: their in-zone percentiles span from the 1st all the way to the 100th percentile as pitchers grapple with choosing where to pitch. For a player like David Fletcher, who makes contact outside the zone more often than most hitters do on pitches inside the zone, pitchers seemed to concede that fact and throw strikes. Anthony Santander, who rarely walks, was pitched to outside the zone frequently, but found success in 2020 regardless as he makes good contact there.

In general though, have pitchers been making use of these discrepancies? It appears they have, but very modestly. The final scatterplot below juxtaposes the percent of pitches that hitters receive inside the zone versus their in-zone contact and out-of-zone contact discrepancy.

Comparing the first and final scatterplots in this post illustrate the slight shift in how pitchers approach hitters when in-zone/out-of-zone contact rate discrepancies are applied versus simply in-zone rates. Essentially, pitchers seem to take in-zone/out-of-zone contact differences into account, if only modestly.

Whether or not pitchers are leveraging that difference in contact percentages enough remains to be seen, as omitted variables doubtlessly impact how any individual hitter is approached. Making sweeping assumptions isn’t advisable either, especially when comparing only the dichotomies like that of in-zone pitches and out-of-zone pitches, without offering additional context. Still, the above suggests that these discrepancies were on the radar of MLB pitchers in 2020, at least to some degree.