NEW YORK — Rob Manfred envisions more experiments with speed-up rules, such as limiting pitching changes and trips to the mound, or requiring each pitcher to face multiple batters.

The new baseball commissioner said he doesn’t see any need to expand the designated hitter to the National League. Manfred also expects teams and the players’ association to discuss possible changes to September call-ups during collective bargaining for a contract that starts before the 2017 season.

Concerned the average time of nine-inning games climbed to 3 hours, 2 minutes in 2014, owners and players agreed to install clocks to time between-innings breaks and pitching changes, and to require hitters to keep at least one foot in the batter’s box in many instances. The average has dropped to 2:56 this season.