MLB – and all of the US professional sports leagues – prohibit players from betting on their own sport. MLB players who bet on their own teams face a lifetime suspension. The penalty for betting on other teams is up to one year.

San Diego Padres infielder Tucupita Marcano was named by the WSJ, which also reported four minor leaguers are under investigation. It’s not clear if the players were betting legally or illegally. Marcano is being investigated for betting on baseball and the Pittsburgh Pirates. He was on injured reserve last season.

US professional sports have been under a microscope with regard to gambling of late. Former NBA player Jontay Porter was banned from the league for life on 17 April after violating league gambling rules. Porter bet on himself and his Toronto Raptors. In 2023, ten NFL players were suspended for various lengths of time for violating league wagering rules. And the NHL last October banned Ottawa Senator Shane Pinto for betting.

MLB hit with multiple betting scandals

The news of the MLB investigation broke on the eve of former Shohei Ohtani interpreter Ippei Mizuhara’s plan to plead guilty to fraud and one other count for stealing $17m from Ohtani to pay off illegal gambling debt. Mizuhara allegedly bet on baseball and other sports with illegal bookmaker Mathew Bowyer. Bowyer has been connected to the Wayne Nix gambling ring.

Nix is a former minor-league baseball player who ran an illegal bookmaking business in Orange County for 20 years. Bowyer is under federal investigation, but has not yet been charged. Nix is set to be sentenced in federal court in September.

Two other professional baseball players are under federal investigation in relation to the Nix ring. On 17 May, ESPN linked former Angels infielder David Fletcher and ex-minor leaguer Cody Shultz to the illegal betting ring. MLB has reportedly opened a betting investigation into Fletcher, now in the Atlanta Braves farm system.

Marcano is on the injured list recovering from ACL surgery. He entered the league in 2016 when the Padres signed him as an international free agent. He made his major-league debut 1 April 2021, but was traded to the Pirates 26 July 2021. Last season, he was back and forth between the Pirates big-league team and its Triple A Indianapolis Indians. On 25 July 2023, he was placed on injured reserve.

Sports betting is legal in Pennsylvania and Indiana. If Marcano signed up with a legal operator using his own personal information, his account would have been flagged.

Legal operators have access to exclusion lists and professional rosters, and pay special attention to accounts created by professional athletes. MLB players are within the bounds of league betting rules if they bet on other sports.

The WSJ did not name the minor-league players under investigation. The paper also reported that MLB and the MLBPA declined to comment.

“We are aware of an active investigation by Major League Baseball regarding a matter that occurred when the player in question was a member of another organization and not affiliated with the San Diego Padres,” the Padres said in a statement. “We will not have any further comment until the investigative process has been completed.”