Major League Baseball enacted several significant changes to squeeze in the 60-game 2020 season due to COVID-19. Some of those changes remain in effect for what everyone hopes will be a full 162-game slate this year, with others reverting to previous levels. Here’s a look at what’s different and what will be the same for 2021:

Designated Hitter

What it used to be: The National League employed a full-time DH last season for the first time, nearly a half-century after the American League adopted the rule in 1973. Since interleague play began in 1996, the NL used the DH only in those games played in AL parks.

What it will be: Pitchers will bat again in the National League in 2021, although the longtime debate over unifying the rules in both leagues could lead to the universal DH being employed in both leagues in the next collective bargaining agreement negotiations, slated for later this year.

Expanded Playoffs

What it used to be: MLB’s playoff format was stretched from 10 teams to 16 in 2020, with all eight participants in each league playing a best-of-three wild-card series before the Dodgers eventually defeated the Rays in the World Series.

What it will be: MLB still hasn’t officially announced whether it will continue with the new format. If not, it is expected to revert to the previous one that featured MLB’s six division winners, with two wild-card teams in each league facing off in a one-game playoff.

Roster Size

What it used to be: Due to the delayed start and condensed schedule, teams were allowed to carry 30 players on their active roster for the first two weeks of last season and 28 for the next two weeks before rosters were reduced to 26 for the rest of the year. Each team also was permitted a three-player taxi squad for road trips, with the rest of the teams’ 60-man player pool working out at an alternate training site.

What it will be: Rosters will contain 26 players, increasing to 28 in September, with no limit to the number of pitchers on a team’s roster. Each club also is permitted to carry up to five additional taxi squad players on all road trips.

Attendance

What it used to be: No fans were allowed in MLB parks in 2020 until limited amounts were permitted inside the bubble setups in the NLCS and the World Series, which were played in Arlington, Texas. No fans attended games in the ALCS in San Diego.

What it will be: Not all plans are finalized in each state, but all 30 teams were planning for the return of fans, mostly in limited numbers, beginning on Opening Day, including 20 percent announced capacities at Yankee Stadium and Citi Field.

Doubleheaders

What it used to be: To limit time spent at the ballparks due to the pandemic, MLB instituted seven-inning doubleheaders in 2020. There were 45 games postponed due for COVID-related reasons, with only two eventually not played.

What it will be: MLB is sticking with this rule after 56 twin bills were played last season, the most since there were 76 in 1984.

Extra innings

What it used to be: MLB implemented a first-time rule change last year in which teams started each extra half-inning with a runner on second base.

What it will be: MLB also is sticking with this alteration here to avoid lengthy games. There were 78 extra-inning games in 2020, none lasting longer than 13 innings.

Minor Leagues

What it used to be: All minor league seasons were scrapped last season, with prospects not listed on a team’s 40-man roster eligible to be included on their 60-player pools and permitted at their alternate training sites.

What it will be: Dozens of minor league affiliates across baseball were eliminated in cost-cutting measures. MLB also will test a few new potential rule changes in the minors this year, including larger bases (Triple-A), infield positioning restrictions (Double-A) and a 15-second pitch clock and limited pickoff attempts (Single-A), among others. Teams will use alternate sites for the first month, with minor league seasons not scheduled to begin till May.