
The new labor agreement between MLB and the MLBPA will include a number of changes, some more significant than others. It will take some time to digest all the differences, but one significant one will be noticeable quite quickly.
Advertising will be allowed on MLB uniforms for the first time as part of the agreement, as first reported by Jeff Passan of ESPN.
This will come in the form of patches on jerseys, as well as decals on batting helmets.

MLB becomes the latest major pro sports league in the United States to embrace the practice of jersey advertising. The NBA kickstarted the process in 2017, while the NHL will introduce jersey ads starting in the 2022-23 season. It is not initially clear if MLB teams will have jersey sponsors in 2022 or whether that will be pushed to 2023.
The NFL is the last holdout in terms of jersey ads, but it may be inevitable at this point. Even small patches on NFL jerseys would likely net the league significant amounts of money.