Examining Early Returns on MLB's New ABS (Automated Ball-Strike) Challenge System

[Mike Gillespie]

Image courtesy of © Mark J. Rebilas-Imagn Images

The major leagues’ newest product-improvement innovation is in full spring training flower. Baseball purists may not like it, critics of the current state of umpiring might not think it goes far enough, and it doesn’t appear likely to offend Commissioner Rob Manfred’s game pace sensibilities.

But the Automated Ball-Strike Challenge System (ABS, obviously, for short) is here, running through its final paces in the Cactus and Grapefruit Leagues before officially becoming a highly visible part of the big league game on Opening Day. And even before its regular season debut, ABS has spawned new statistics sure to satisfy the palates of those hungry for additions to baseball’s already packed metrics menu.

And not surprisingly, Baseball Savant is taking the lead with ways to deep-dive ABS. Savant has numbers for crunchers seeking everything they can get, and for fans for whom just a quick look under the hood will suffice.

Baseball Savant’s Basic Approach to ABS Analysis

Take Savant’s more basic version of ABS first. For both batter and fielder challenges (only hitters, catchers, and pitchers can dispute pitch calls), it counts how many times called balls and taken strikes were challenged, the won-loss results of those challenges, challenge rates (actual vs. potential challenges), and total “flips”—challenges which reversed a strikeout or a walk.

Through Friday’s exhibition games, this basic Savant data reflected that 53% of challenged plate umpire calls had been overturned. It had the Yankees and Twins atop the batter breakdown, with their hitters tied for most challenges (15), challenge wins (nine), and winning percentage (60%); New York led in challenge rate (12.2%), and the Twins were second (10.3%). Minnesota led the majors with five “-K Flips" — the number of strikeouts ABS struck down -- and were tied with the Giants, Guardians, and Reds for the top spot in “+BB Flips” — the number of walks resulting from challenge-created fourth balls — with two.

And the worst clubs? The Dodgers and Rangers hadn’t won any challenges as of the close of play Friday, but their hitters had challenged only four pitches (teams begin games with two, lose each unsuccessful challenge, don’t suffer a reduction if they win a challenge, and get extra challenges in extra-inning contests).

Individual batters boasting 100% challenge rates are, at this early stage, too numerous to mention. But Boston’s Wilson Contreras’ four wins ranked first (he’d lost one) while seven players shared the loss lead with two apiece.

Colorado’s pitchers and catchers led in “team” wins with 11. The Yankees had challenged more pitches (16, which helps explain their top challenge rate of 6.5%) but lost more (nine) than any other club. Not surprisingly, no team is completely passing on challenges, although the Mets had disputed only seven calls, and the Cubs disputed only 1.9% of the pitches they could have contested.

Eight individual fielders led with four wins apiece; five tied at the bottom with four lost challenges. 

Baseball Savant’s Deeper-Dive ABS Tracking

Looking for more meat on the ABS analytics bone? Try Savant’s more extensive leaderboard, which offers more ways to filter results (breakdowns by pitch type, for example), success rates for challenges brought by and against teams, and even X-factors like total call overturns vs. expected overturns and expected challenge rates. Here's just a sample of the myriad of results.

Although their 8-6 challenge record wasn't spectacular, the Brewers' batters led the way with a net 2.9 overturns vs. expected overturns rate, while Kansas City’s poor -3.7% overturns vs. expected rate brought up the rear. Washington's 6.7 batting team expected challenge rate (the percentage of challengeable pitches actually challenged) was the majors' best, while Miami's 3.8 was the worst. 

That the Yankees and Twins placed players at the top of the expanded individual hitter leaderboard isn’t shocking — tied at 2.5 for the lead in overturns vs. expected overturns rate were New York’s Jose Caballero and Minnesota’s Brooks Lee. Seattle's Jared Sundstrom led batters with a 43.2% expected challenge rate, while Philadelphia's Dylan Campbell and Colorado's Zac Veen had minuscule 0.5% numbers.

Among fielders, Cincinnati’s P.J. Higgins stands out. He was leading catchers with a 2.6 overturns vs. expected mark, and his +6.2% "rate vs. expected" rate (what Savant describes as the "actual - expected" percent of challengeable pitches a player challenges) ranked behind only the Yankees’ Miguel Palma’s +7.8%. Philadelphia catcher Rafael Merchan’s -2.8 was the worst in overturns vs. expected challenges, and Ranger Willie Maciver’s -2.8% result was the worst challenge rate vs. expected mark.

As for pitchers, Minnesota's Justin Topa had the best (2.8) and the Yankees’ Kevin Castro the worst (-1.9) overturn vs. expected numbers. Texas’ William Bormie paced hurlers’ challenge rate vs. expected rates with +94.7%, while Miami pitcher Josh Ekness’ -5.5% was dead last.

What Does All This ABS Data Mean?

Good question, but one that can’t be satisfactorily addressed based on a week of exhibition games. The sample size is just too small. 

Not until well after Opening Day, when much more data is available, should analysts, media types, and fans try to form solid conclusions. Only then will they have begun to get good feels for strategies, why some challengers are better than others, and which teams are mastering the new art. And those early conclusions may only scratch the surface.

Things are about to get interesting.

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[LewFordLives]

I hate the challenge system. It ruins the flow of the game and slows things down. I don't understand why they don't just move to full ABS. The umpire can still physically call out ball or strike if he needs something to do. The home plate umpire would still also be plenty busy managing other aspects of the game.

[Brock Beauchamp]

4 minutes ago, LewFordLives said:

I hate the challenge system. It ruins the flow of the game and slows things down. I don't understand why they don't just move to full ABS. The umpire can still physically call out ball or strike if he needs something to do. The home plate umpire would still also be plenty busy managing other aspects of the game.

My understanding is that the fully automated system *really* slows down the game. It's probably going to take a few years of refinement to reduce the lag.