The rule changes for 2020 in Major League Baseball have been officially announced. The change that had not really been mentioned in previous reports is that managers now have 20 seconds to challenge a play rather than the 30 seconds previously available. The other changes, by category, are as follows.
Designating Players & Who Pitches
Clubs must designate each player as either a position player or a pitcher before his first day on an active roster in a given season. Position players can only pitch if they are (1) a 2 way player (requires 20 MLB games started as a position player or a designated hitter with three plate appearances per game); (2) the game is in extra innings; or (3) the player’s team either leads by six runs or is down by six runs. Pitchers must either pitch to three batters or until the end of a half-inning, unless they become injured.
Pitchers and 2 way players must now stay on the injured list 15 days. For position players the minimum time spent on the injured list remains at ten days. These minimum times also apply to optional assignment to the minor leagues.
The roster is a 26 man roster from opening day through August 31 under ordinary circumstances. For doubleheaders, the roster can now be 27 men. The minimum number of active players rises from 24 to 25. The maximum number of pitchers on the roster is ordinarily 13, although that increases to 14 on September 1st and for doubleheaders. The overall roster maximum for September 1 through the end of the season is now 28 men.