NEW YORK — Seven-inning doubleheaders and runners on second base to start extra innings will return for a second straight season under an agreement for 2021 health protocols reached Monday between Major League Baseball and the players’ association.

The deal did not include last year’s experimental rule to extend the designated hitter to the National League or expanded playoffs. After allowing 16 teams in the postseason last year instead of 10, MLB had proposed 14 for this year before withdrawing that plan last month.