New pace of play stuff and related rules:
Pitch clock - deferred until they see how other things work / don't work
Video review rooms - new equipment (which will be monitored) was installed to prevent teams from using video review to steal or relay signs
Mount visits - 6 per team per 9 innings, additional 1 per inning for extra inning games. Any manager, coach, or player visit counts, but pitching changes, cleaning cleats if rainy, or injury checks do not. Ump can grant additional visits if he believes a cross-up has occurred.
Between innings and Pitching changes - 2:05 for local games, 2:25 for national games, 2:55 for postseason games. Pitcher must throw their final warmup pitch no later than 20 seconds before this, and must start throwing first pitch when clock hits 0.
Additional Warmup - No limit to warmup pitches or minimum guarantee, but final pitch must occur in time frame above.
Umpire can grant time extensions if he believes there is a danger to the player not to do so, or if there's an equipment issue, etc.
https://www.mlb.com/news/mlb-announces-pace-of-play-initiatives/c-266718664