The ABS Effect: Catcher Receiving and Run Value impact

I built this project to look at how MLB's new Automated Ball Strike Challenge System has changed catcher defense in its first year. I pulled data straight from Baseball Savant, FanGraphs, and Statcast, along with reporting from ESPN, MLB.com, and a few other outlets, and compared catcher framing leaderboards across 2024, 2025, and 2026.

The biggest finding is about Patrick Bailey. He led all of baseball in framing runs in both 2024 and 2025 while with the Giants, but in 2026 he fell out of the top 5 entirely. A rookie, Brandon Valenzuela of the Blue Jays, now leads the league instead, alongside names like Adley Rutschman, Alejandro Kirk, and Dillon Dingler. I didn't want to just credit that drop to the new rule though, so I dug into it further and found Bailey was actually traded to Cleveland in May 2026, meaning he spent most of the season learning a brand new pitching staff. That is a real factor on its own, separate from ABS, and I made sure to call that out instead of oversimplifying the story.

League wide, framing value among the top catchers dropped about 20 percent, from 0.704 runs per 100 innings in 2025 down to 0.565 in 2026. I also looked at the challenge system itself: catchers and pitchers have been right on their challenges about 59 percent of the time, compared to 45 percent for hitters, across more than 7,000 challenges and over 3,500 overturned calls this season. One catcher I highlighted is Tyler Stephenson of the Reds, who actually grades out poorly in traditional framing metrics but has recovered a lot of that lost value through the challenge system itself, going 32 for 42 on challenges. Link: ABS_Effect_Catcher_Framing_Analysis.docx