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Baseball is officially back, as MLB and the MLBPA ended their 99-day lockout Thursday by agreeing to a new collective bargaining agreement. Once play resumes, fans will notice something different about their teams' jerseys: advertisements. 

For the first time in MLB history, the league's player uniforms will reportedly feature advertising. Advertisements will appear via patches on jerseys and decals on batting helmets.

Jersey advertisements – which have long been seen in Europe, Asia and Latin America – have become nearly ubiquitous among major U.S. professional sports leagues. MLS introduced them in 2007 and the NBA followed suit in 2017. They already appear on NHL helmets, and last August, NHL owners agreed to add them to uniforms in their league in the 2022-23 season. NASCAR has long featured advertising on its drivers' cars and racing suits. 

After MLB's decision, the NFL is now the only league without plans for jersey advertising. 

The NBA is the most recent league to add jersey advertising, and the move has already paid off handsomely. According to Boardroom, the jersey patch program produced a combined value of $225 million for the 2021-22 season, over double the league's original estimates. 

"We've seen tremendous growth from this asset [in terms of both] revenue and the caliber of brands, both domestic and global, that are partnering with our teams," NBA president of team marketing and business operations Amy Brooks said last December. 

Along with jersey advertising, MLB will introduce the following as part of its new CBA: a 12-team postseason; designated hitters in the National League; a draft lottery for the first six picks; draft-pick inducements; limits to the numbers of times players can be optioned to the minor leagues;  and a 45-day window for MLB to implement rules changes. 

The 2022-23 MLB season is slated to begin April 7, seven days later than originally planned. Free agency began Thursday night while spring training will open Sunday, March 13.