The NFL, MLB, MLS, NBA, NHL and their players’ unions sent a letter to state gaming regulators on Tuesday, asking them to introduce regulations banning bettors who harass athletes and staff, in response to the “escalating threat” of harassment and violent threats from gamblers. “Too often, individuals who lose sports bets direct threatening and harassing messages toward players, coaches, and their families via social media and in-person interactions,” the groups wrote in the letter. Athletes across sports have increasingly spoken out about harassment and threats received by bettors...