Baseball Needs To Define a Check Swing, Because This Ain’t It

What is a check swing? There's actually no rule defining it, which is going to become increasingly apparent as the ABS challenge system moves closer to implementation at the MLB level.

Commissioner Rob Manfred revealed on "The Dan Patrick Show" earlier this week that MLB will test the ability to challenge pitches in Spring Training next year. 

This system was used at Triple-A from June 25 on during the 2024 season, with each team getting three challenges per game, and more than that if they get any right. Under this system, umpires still call balls and strikes, but players and managers can go to a tennis style instant review system to attempt to overturn what they believe are incorrect calls: 

The challenge system seems to make more sense than a fully automated zone, although there are definitely people on the other side of this debate. From here, there's an art to good catchers stealing strikes on borderline pitches that they frame well that is part of the game and shouldn't go away. This system keeps that in, but allows for corrections to the most egregious calls. 

Manfred would go on to say that he expects some version of ABS — whether it's the challenge system or just a full-on automated zone — to be at the MLB level in the next four years. 

There are still some kinks that need to be worked out in the system, with the aforementioned lack of a check swing definition at the forefront. Take, for example, this review in the Arizona Fall League earlier this week: 

Another example of the checked-swing review system from last night. pic.twitter.com/ifi2c6pkhJ

— Josh Norris 🐻 (@jnorris427) October 23, 2024

OK, there isn't an exact definition of a check swing. But does anyone think that if you go this far past home plate it shouldn't be considered a swing? 

Maybe there are people who use this diagonal line to determine whether someone checked a swing. I don't know any of them. Most people seem to think it's whether your bat and/or front hip goes beyond the front of the plate. I've always viewed it as if your bat broke the plane of the front of home plate, you swung. If not, you checked. 

As much as I don't want a fully automated zone, check swings are one of the more ridiculous things to have humans — ones who aren't even in great position to get a good view — still determining. Whether it's Ryan Howard or Bryce Harper, there have been some notable ejections in Phillies history over missed check swing calls. The challenge system could fix that. 

First, though, baseball needs to decide what a check swing actually is and define it. Hopefully it doesn't take them as long as the NFL needed to decide what a catch was.