MLB will use experimental rule changes in 2021 minor-league season: Defensive shift limits, robot umps, more | CBS Sports Headlines MLB will use experimental rule changes in 2021 minor-league season: Defensive shift limits, robot umps, more The rule changes are designed to create more balls in play and shorten the … Continue reading MLB will use experimental rule changes in 2021 minor-league season: Defensive shift limits, robot umps, more