We have players like Emmanuel Clase and Luis Ortiz who have been suspended from MLB for alleged rigging of games. And legends like Pete Rose, who have been permanently banned from MLB for betting. But MLB just let Ronald Acuna Jr. walk into a partnership with Kalshi, and one sports reporter is not happy.
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“Now an active MLB player is partnering with a prediction market that MLB is reportedly considering a league-wide deal with. You can understand why people might have questions about that,” said Michaela Bennett.
Ronald Acuña Jr. has become the first MLB player to partner with a prediction market, joining Kalshi as baseball’s gambling debate continues. The commercial aired on Wednesday during Game 4 against the Los Angeles Dodgers, where the Atlanta Braves lost 4-1 and were eliminated from the playoffs.
Kalshi is trying to expand its presence across baseball while looking to add recognizable players to its roster. Acuña’s deal is a major step for the company, but MLB’s long history with gambling makes this partnership different from ordinary athlete endorsements.
In August 2026, the company announced partnerships with the Braves, Boston Red Sox, Dodgers, San Diego Padres and San Francisco Giants. Kalshi also reported that baseball-related trading volume had increased 36-fold year over year, showing the market’s rapid growth.
With five teams already involved and a reported league-wide deal under discussion, the company is building a bigger presence around MLB.
And Acuña gives that expansion a recognizable face, backed by achievements that have made him one of the sport’s biggest stars.
He won the National League MVP award in 2023 after hitting 41 home runs and stealing 73 bases, becoming MLB’s first 40-70 player. His eight-year, $100 million extension with Atlanta also reflects how early the Braves committed to building around him. For Kalshi, Acuña’s status gives the platform credibility with baseball’s most engaged fans.
However, the partnership arrives as baseball continues to draw strict boundaries around player involvement in gambling.
MLB prohibits players from betting on baseball, and its 2025 guidance specifically warned against wagering on baseball-related prediction markets like Kalshi. However, Acuña’s endorsement does not automatically violate those rules, and without the deal’s exact terms or official confirmation, its full compliance remains unclear.
Acuña’s endorsement does not itself indicate a rules violation, but it draws a very thin line between promoting a platform and trading on baseball outcomes.
Baseball has already seen players face serious consequences after violating those rules, even when their bets did not affect games.
In 2024, MLB permanently banned Tucupita Marcano after finding he placed 387 baseball bets, including wagers involving the Pittsburgh Pirates while with the team.
In November 2025, Clase and Ortiz were indicted for an alleged scheme involving rigged pitches and fraudulent wagers, highlighting how player betting can compromise game integrity.
Legends like Pete Rose accepted permanent ineligibility in 1989 after an investigation into his betting on games while managing Cincinnati. MLB removed Rose and other deceased individuals from its permanently ineligible list in May 2025. But that black spot will always remain.
For MLB, protecting the credibility of every pitch and every at-bat remains essential as prediction markets attract more attention from fans and companies.
But there is no evidence Acuña has ever engaged in gambling misconduct, and the partnership itself does not suggest wrongdoing. But his status as a former MVP and the face of a major franchise means the partnership will attract eyeballs.
As prediction markets move deeper into baseball, the league faces a choice. The league must balance new business opportunities with protecting the game’s integrity and its players.
MLB players have had enough of gambling-related harassment
Baseball players are now facing a growing problem as sports betting brings angry gamblers closer. This harassment context makes Acuña’s Kalshi deal controversial because in 2025, The Athletic surveyed 133 players, and 78% said betting changed how fans treated them or their teammates.
A separate 2026 survey found 81 of 100 players faced confrontations over betting losses.
These numbers show how gambling has changed the relationship between players and fans. A missed strikeout or surrendered home run can now follow players home through angry messages.
The harassment has gone beyond complaints, with players receiving threats against themselves and their families. Former Mets pitcher Ryne Stanek described the messages angry bettors sent after losing their parlays.
“You cost me your parlay, I hope your family dies,” was one threat he recalled. Other players have also described receiving death threats and seeing their home addresses shared online.
Legal sports betting has increased players’ exposure to gamblers who blame them for lost wagers. One American League East pitcher described receiving a $3,000 Venmo request after a game.
The bettor wrote, “You cost me my parlay. Let’s do the right thing.”
The same bettor reportedly sent another $3,000 request after a later outing.
Players are now dealing with demands for money over bets they never asked fans to place.
This pressure has pushed players’ unions to seek stronger protections against betting-related harassment. And that is what makes Ronald Acuna Jr.’s partnership with Kalshi even more questionable.
Although the deal doesn’t establish his personal position on harassment, he just signed for something the players have been fighting against.