While Major League Baseball has been experimenting with extra-inning rule changes in the past few years, the Pioneer League -- an independent team designated as a MLB Partner League -- is carrying things a step further.
"Under the rule, each team designates a hitter who receives five rebounds, with the match dependent on the most home runs hit," stated a news release announcing the rule changes. "If still tied after the initial'Knock Out' around, another hitter is selected to get a sudden-death home run face-off until a winner is declared."
Also, a hitter may appeal a check swing attack decision to some base umpire. Under standard baseball rules, just the defensive staff can ask for an appeal.
While the Pioneer League is a partner league with MLB, there's not any official tie with MLB experimenting with all these potential rule changes. MLB previously announced a partnership with an independent Atlantic League to examine rule changes, such as transferring the pitching rubber back a foot and a double-hook rule in which a group will lose its own designated hitter when it removes a starting pitcher.
MLB also lately instituted rule changes in the minor league level including larger bases, regulations of this shift and forcing pitchers to step off the rubber entirely before throwing to a foundation.