The independent Atlantic League is so pleased with "robot umpires" that it will continue using the system for the rest of the season, according to a source.
The league became the first American professional baseball league to let a computer call balls and strikes at its All-Star Game earlier this month.
After the successful test, the league started rolling out the technology to stadiums throughout the league.
The umpires have the ability to override the computer, which considers a pitch a strike when the ball bounces and then crosses the zone. TrackMan also does not evaluate check swings.
"We're very excited about what this portends not only for our league but for the future of baseball," president Rick White said. "What we know is technology can help umpires be more accurate, and we're committed to that. We think the Atlantic League is being a pioneer for all of the sport."