NBA players have always gotten an earful from fans, whether at home or on the road. It comes with the job.

But this season, it’s getting darker.

The recent surge in legalized gambling in every pro league, and throughout college athletics, has impacted American sports in ways thought unimaginable just a few years ago. But along with the potential good that hundreds of millions of dollars in new revenues bring to the NBA and other leagues, something new and ominous has arrived: verbal abuse directed at players and coaches based solely on fans’ wagers.

Fans can now bet in real-time on their smartphones, on all aspects of the game.