Just ahead of Opening Day being delayed because of the COVID-19 pandemic, Major League Baseball formally adopted some notable rule changes designed to speed up the game when the 2020 season is finally launched.

Here's the lowdown:

Three-batter minimum

This is the most radical revision. All pitchers－both starters and relievers－are now required to face at least three batters or continue pitching until the inning is over before they can be replaced.

The lone exception is for an in-game injury or illness that prevents the pitcher from being able to face the minimum.

Specialist relievers, often used for only one batter to give their team a favorable matchup－for example, a southpaw who faces only left-handed batters－will be impacted the most.

The rule will also affect teams that use relief pitchers to open a game against the top of the opposing order－a strategy that was widely used last season. Now, any starter will have to face at least three batters regardless of unfavorable matchups during his stint.

Position players pitching: Position players are now only allowed to take the mound if a game is extended to extra innings or if their team is winning or losing by more than six runs.

During normal circumstances, only the team's 13 designated pitchers are allowed to pitch in a nine-inning game.

Last season, more than 50 different position players pitched in at least one game, thus allowing teams to save their pitchers' arms if they felt a game was out of hand.

Challenge time

Managers now have only 20 seconds to challenge a play instead of 30, thus limiting their time to access information to request a video replay. This is expected to dramatically reduce the number of video challenges at first base, which could have a negative impact on scoring.

While these rule changes have been officially adopted, MLB is still exploring ways to increase scoring in order to avoid a propensity of extra-inning games－something Los Angeles Dodgers third baseman Justin Turner sees as a unique opportunity.

In an interview with Access Sportsnet last week, Turner proposed a tie-breaking home-run derby to limit the length of games and save potential wear and tear on pitchers' arms.

Think of it as MLB's equivalent of how the National Hockey League uses shootouts to decide regular-season games.

"This is my opportunity to push for a home-run derby instead of extra innings," said the 35-year-old Turner, who hit.290 with 27 homers and 67 RBIs last season. "Instead of playing 17 innings, you get just one extra. You play the 10th inning, and if nobody scores, then you go to a home-run derby.

"You take each team's three best hitters and you give them all five outs. You know, you wanna keep the fans in the stands until the end of the game. When I go to a hockey game, I love watching the shootout. That keeps me in my seat. I think a home-run derby would do that, too."

Turner's proposal has merit, particularly now with MLB considering several options to play as close to a full schedule as possible if the season is launched. It could mean "multiple doubleheaders" each week and even "seven-inning doubleheaders".

However, if MLB adjusts the extra-inning format, it would likely be more in line with the minor-league format, which starts each extra inning with a runner on second base.

Meanwhile, basing all 30 teams in Arizona this season and playing in empty ballparks were among the ideas discussed by MLB and the players' association in a conference call in New York last week.

"MLB has been actively considering numerous contingency plans that would allow play to commence once the public health situation has improved to the point that it is safe to do so," the commissioner's office said in a statement.

"While we have discussed the idea of staging games at one location as one potential option, we have not settled on that option or developed a detailed plan.

"We continue to interact regularly with governmental and public health officials, but we have not sought or received approval of any plan from federal, state and local officials or the players' association.

"We are not ready at this time to endorse any particular format for staging games in light of the rapidly changing public health situation caused by the coronavirus."

Half of MLB clubs hold spring training in Arizona, the other half in Florida.