Who Wants the Robo-Ump? And Who Doesn’t..

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The Automated Ball-Strike System (ABS), also referred to as “the robot umpire”, is coming to Major League Baseball within the next few years. ABS will certainly have an impact on catchers, who are currently credited or discredited for Framing Runs based on their ability to pull borderline pitches into the strike zone and hold them for umpires to believe they were strikes. But how will ABS impact batters and pitchers? Will superstars no longer get superstar treatment on borderline calls? And who will ABS benefit more - pitchers or hitters?

To answer this, I looked at over 600,000 pitches from the 2023 season to see which players are likely to be impacted the greatest by ABS. 3.75% of all pitches in 2023 resulted in incorrect strike or ball calls by home plate umpires (pitches inside the strike zone called as balls or pitches outside the strike zone called as strikes). I’ll use this dataset of over 20,000 pitches for the remainder of the analysis.

Which Pitchers Will Be Most Affected?

Table 1: Summary of missed umpire calls in 2023

As stated in Table 1, umpires have given pitchers an extra 2,228 strikes this season (net of the actual strikes that they mistakenly called balls). Judging by this number, ABS is primed to spark an increase in offense, which is a primary goal of MLB as they believe a higher run-scoring product is more exciting for fans.

Table 2: The ten pitchers who were given the most extra strikes in 2023.

Table 2 shows the ten pitchers who have been the most positively impacted by missed calls in 2023, along with the net number of missed calls in their favor/against them and the consequent run value and WAR (wins above replacement) impact of the missed calls (click here for explanation on the conversion of missed balls/strikes into run value).

There are some brand names listed in Table 2, including former Cy Young Award winners Blake Snell, Shane Bieber, and Corbin Burnes. The extra strikes this season may be playing a role in the 2023 Cy Young candidacy too. Both American League favorite Gerrit Cole and National League favorite Blake Snell have benefitted greatly from balls calls as strikes by umpires this year.

The average career ERA among the pitchers in Table 2 is 3.55, well below the league average ERA of 4.35. Hence, it seems that umpires are giving the benefit of the doubt on close calls to pitchers with proven track records. Furthermore, Logan Webb and Kyle Hendricks rank in the 98th and 97th percentile, respectively, in walk percentage (i.e., they rarely walk batters). Thus, it also seems that umpires lean towards giving close calls to pitchers with extremely good control.

Table 3: The ten pitchers who had the most strikes taken away from them in 2023

The ten pitchers in Table 3 are the ones who have been most negatively impacted by missed calls this season. They do not have the same track record as the proven aces in Table 2. None of them have won a Cy Young and their average ERA is 4.43, worse than the MLB average.

A perceived lack of control is also problematic for the pitchers in this camp. For instance, Jordan Hicks and Yusei Kikuchi were in the 1st and 3rd percentile in walk rate in 2022. They have both improved their walk rates this season, but they would have improved even more under ABS.

Which Batters Will Be Most Affected?

Table 4: The ten batters who were given the most extra balls in 2023

Table 4 shows the ten batters who have been most positively impacted by missed calls in 2023, along with the net number of missed calls in their favor and the consequent run value and WAR impact of the missed calls.

Shohei Ohtani, a lock for AL MVP despite his second half injuries, and Ronald Acuna Jr., who is in a tight NL MVP race, are both present on the list. Moreover, Wander Franco (before his off-field issues) and Kyle Tucker have established themselves as premier players in the league. The average career OPS of the hitters in Table 4 is .803, well above league average of .736. As we saw with the top pitchers in the league, the top hitters are also receiving the benefit of the doubt on close pitches. The top pitchers, however, get about twice as many close calls in their favor as the top hitters.

Table 5: The ten batters who had the most balls taken away from them in 2023

On the other hand, Table 5 shows the batters who have been most negatively impacted by missed calls. Two names here are surprising: Adley Rutschman and Alex Bregman rank in the 92nd and 87th percentile in walk rate, respectively. Known for their outstanding plate discipline, last year they ranked in the 96th and 94th percentiles in walk rate. Evidently, two of baseball’s most patient hitters are actually not getting rewarded by umpires this year. This may be another testament to umpires weighing the credentials of the pitcher more heavily than those of the batter when deciding on a close call.

And Lastly, Which Catchers Will Be Most Affected?

Table 6: Best framing catchers in 2023, according to Baseball Savant

Table 6 and Table 7 show the ten catchers who will see the greatest drop in value and the greatest increase in value, respectively, when ABS is rolled out, based on their framing ability.

The defensive focus of the catcher position will shift drastically from framing to blocking, throwing, and calling pitches. The catcher position will also shift into more of an offensive position as teams will no longer be able to reap the benefits of framing after ABS is integrated into the majors.

Martin Maldonado, known for his excellent pitch calling, and JT Realmuto, one of the better hitting catchers in the league and an elite thrower, should see a significant bump in value. On the other hand, framing expert Austin Hedges and 2022 Platinum Glove winner Jose Trevino should see a drop in value.

Table 7: Worst framing catchers in 2023, according to Baseball Savant

Conclusion

When ABS is rolled out in the MLB, the game will change in a few ways:

1.      Offensive output should increase, since pitchers are currently benefitting from extras strikes being called.

2.      The relative value of the superstar player should reduce, since superstars are having close calls go their way more often than they deserve.

3.      The value of the control pitcher will reduce and the value of wild pitchers with tremendous stuff will go up. Control pitchers will no longer benefit by having most borderline calls go their way, and wild pitchers will no longer be over-punished for their wildness by having most borderline calls go against them.

4.      Batters with tremendous plate discipline may become even more valuable since they have had more than their fair share of close calls go against them with human umpires.

5.      The catching position will change dramatically, with an added emphasis on offensive production, arm strength and accuracy, and blocking ability replacing framing.