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Check swing replay system comes a few years too late for SF Giants

This sure would've been nice in 2021.
Nick San Miguel
Nick San Miguel

Around the Foghorn

Division Series - Los Angeles Dodgers v San Francisco Giants - Game Five / Harry How/GettyImages

With the Arizona Fall League implementing a replay system for check swings, SF Giants fans cannot help but think that this change came a few years too late. It remains to be seen whether this will be implemented in MLB.

Giants fans do not need to be reminded of how Game 5 of the 2021 NLDS against the Los Angeles Dodgers ended, but any conversation about check swings unfortunately must go down this dark road.

SF Giants fans wish check swing replay came sooner

Wilmer Flores checked his swing on an 0-2 pitch against Max Scherzer in the bottom of the 9th inning with the Giants down 2-1 and a runner on first. I will link the video here if for whatever reason you are feeling masochistic today and want to relive one of the most gut-wrenching moments in franchise history. 

Clearly, Flores did not swing. He checked his swing and the home plate umpire appealed to the first base umpire Gabe Morales who decided it was a swing. We know that check swing calls are very difficult for umpires, but Morales blew the call and decided to take the fate of that game into his own hands. With how epic the race for the NL West was that season and with how good that NLDS series was, it was an absolute shame that it came down to the flawed opinion of one umpire.

That was in 2021. Now, in 2024 they are currently using a new system in the Arizona Fall League that allows batters to challenge check swing calls. What they are defining as a check swing is if the swing goes beyond a 45-degree threshold from home plate. You can watch a video here to see what it looks like in practice. 

If you compare the “swing” Flores took to what would be considered a swing under these guidelines, Flores did not come anywhere close to crossing that 45-degree line.

We will have to see whether this system gets implemented in MLB at some point. Recent changes and experiments like the pitch clock, automatic balls and strikes, and banning the shift have all been tried out in the AFL. That does not mean the check swing replay system will be in MLB next season, but it certainly means it is something we could see within the next few years.

If they do ever implement this system, Giants fans will forever be bitter that it did not exist when Flores was erroneously rung up by Morales and the Giants had their season ended based on a completely subjective call. 

Nick San Miguel

Nick San Miguel

Nick San Miguel has been writing at FanSided since 2017. He began as a contributor writing about the San Francisco Giants at Around the Foghorn and became a Site Co-Expert for AtF in 2024. A die-hard Bay Area sports fan born 10 minutes from Levi's Stadium, he has also written about the San Francisco 49ers for Niner Noise as a contributor since December 2023. In October 2025, he joined Blue Man Hoop as a contributor to write about the Golden State Warriors. He graduated with a degree in History from San Diego State University and is now based out of Chicago. He is the same age as Oracle Park.