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The Joe Sheehan Newsletter: ABS Data Dump
Vol. 18, No. 29
May 11, 2026
Watching games over this last week, it seemed to me that batters had pulled back a lot on their use of challenges. Rarely did an inning go by when I didn’t see a pitch outside the zone go unchallenged by the batter. Some were understandable given game context, but all too often batters were just accepting bad calls in spots with runners on base, or in key counts, or late in a close game...or all of the above. It was as if a memo had gone out about two weeks ago to stop showing up the umps. This, to me, was reflected in a decline in walk rate -- from 9.6% in Marpril to 9.1% in May -- and in overall offense.
Unable to let this go, I went digging last night and found Tap to Challenge, a site that is collecting and publishing detailed challenge data that goes beyond even the information at Baseball Savant. I ended up collecting a bunch of data from the two sites that...didn’t really help me at all.
To start at the top, here’s the breakdown of challenge rates by month:
Bat Cat Pit Chal/G
Marpril 46.2% 51.7% 2.1% 4.12
May 46.7% 51.7% 1.6% 4.01
So if you squint really hard...you still can’t see anything. The primary trend is that pitchers are being squeezed out of the process. They challenged 41 times in Marpril and less than once a day in May. Before challenging four times yesterday (going 1-for-4), pitchers had challenged just five times in the month’s first nine days. It’s pretty obvious why this is happening: Catchers are converting 60% of their challenges, pitchers just 37%. (Hitters are at 46%.) We might be down close to zero pitcher challenges before the year is out.
Tap to Challenge has every challenge made, and you can sort them by day. Maybe there’s a trend playing out that’s being hidden by my ties to the Gregorian calendar? I broke down the challenges by week ending Sundays.
Bat Cat Pit
Week #1 44.5% 52.0% 3.4%
Week #2 46.3% 51.7% 1.9%
Week #3 47.9% 50.0% 2.1%
Week #4 44.8% 53.4% 1.8%
Week #5 47.2% 50.4% 2.4%
Week #6 45.2% 53.5% 1.3%
Week #7 46.9% 51.2% 1.9%
The data are bouncy, though generally telling the same story -- catchers eat up a little more than half the challenges, pitchers are slowly being squeezed out of the process.
Let’s run at this from a different direction, as what I’m trying to find is inaction rather than action. Tap to Challenge tracks “Missed Opportunities,” which in addition to almost being the title of a great song, is closer to what we’re looking for. When did a batter have challenges left, take a pitch outside the zone for a strike, and decline to challenge?
Missed Miss/G
Week #1 214 4.55
Week #2 351 3.82
Week #3 357 3.80
Week #4 383 4.03
Week #5 366 3.94
Week #6 360 3.91
Week #7 376 4.00
This is a little closer to evidence for the thesis. The data directionally supports my theory that for a couple of weeks, hitters got comfortable challenging marginal calls, and since then, they’ve pulled back some. How about the batteries?
Missed Miss/G
Week #1 154 3.28
Week #2 312 3.39
Week #3 328 3.49
Week #4 345 3.63
Week #5 326 3.51
Week #6 267 2.90
Week #7 296 3.15
Now we may be getting somewhere. For the season as a whole, pitchers and catchers have been less likely to decline an opportunity to challenge than hitters were. That trend has accelerated over the last two weeks, as the defense leaves fewer challenges -- fewer uncalled strikes -- on the table, while hitters are not being as aggressive, instead accepting bad strikes at a higher rate.
Is that enough to make up a half a percentage point of walk rate? Seems to me it is. If the challenge system just turns into something else that tilts the game towards pitchers, it’s not going to help baseball’s gameplay issues. In May, in addition to walking less, the league is hitting an execrable .235/.311/.379. There were just 97 runs scored on Sunday, just 91 outside of Calvinball, a mere six runs per game. In May, teams are scoring just 8.13 runs a game in regulation.
Most coverage of the challenge system has focused on individual success and failure rates. That conversation just doesn’t interest me much. In the same way that umpires have been guessing on the margins for years, the players are now. If there is any skill to be revealed, it will take years, if ever, to do so. The rules of the challenge system dirty the waters as well. Some pitches aren’t challenged because they don’t matter much. Other pitches late in games get challenged because the leverage is high or a team takes a shot with two challenges left, even though the pitch has pretty clearly been called correctly. Challenge success rates as tracked are both missing information -- the decision to not challenge -- and including information that has little to do with strike-zone judgment.
No, the importance of the challenge system is in its potential to level the playing field between batters and pitchers. I do think it’s done that a bit. As I have said many times, ABS has largely eliminated the high-leverage strike on a pitch well outside or well below the zone. I’ve already lost count of the times an umpire, overeager to do his little punchy dance, calls “strike three” on a pitch that’s clearly not in the zone, gets challenged, and the system deems the call wrong. Every time that happens, an angel gets its wings.
These trends, though, are a problem. If hitters become timid, relative to catchers, about challenging, then the advantage shifts back to the batteries. They already have a higher success rate, and if they are flipping more of the marginal calls back to themselves, that will take hitters’ counts and walks out of the league, replacing them with pitchers’ counts and strikeouts.
We’re not going to see changes to the challenge system on the fly. It’s my hope we jump from this scheme to full automation. If we were going to make a change, though, it would be this: Give the hitters more challenges than the fielders. Maybe the first wrong challenge for a team’s batters is free. It would be a small step in leveling what seem to be some imbalances in the current rule set, and help give the league’s hitters an extra weapon against the nastiest pitchers who have ever played the game.
