Since commissioner Rob Manfred took over in 2015, Major League Baseball has faced several key challenges — from navigating a COVID-shortened season and a contentious labor battle to controversies about sticky substances on the mound and the baseballs used across the sport. Now with spring camps set to open this week, MLB is about to embark on perhaps its greatest challenge yet: implementing dramatic on-field rule changes designed to make baseball more entertaining and played at a better pace.

Bigger bases, a pitch clock and rules clamping down on the infield shift headline the changes that will debut when spring training games begin on Feb. 24. These changes are part of MLB’s long-term vision for a faster-paced, action-packed future of the sport.

While these new rules have been accompanied by plenty of criticism, particularly by players who believe they are too quickly-implemented and too drastic, the league is confident the game will end up in a better place because of them. Mostly, the commissioner believes that MLB is listening to its fans.

“If you’re addressing what the fans want, you’re more likely than not to get it right,” Manfred said in a recent phone interview with ESPN.

“There’s an initial wave, where it’s ‘Oh my god, (we’re) going to ruin the game. But people see it and get used to it, and a lot of it turns positive for a lot of people.”

So, what rules are changing?

Let’s start with the pitch clock: With the bases empty, pitchers will now have 15 seconds to begin their motion once the catcher returns the ball to them and 20 seconds between pitches with runners on.

Pickoff attempts will be limited: Pitchers will also only be allowed two disengagements from the rubber — the number of times he can step off to throw to a base or to get a new sign.

Teams are no longer allowed to shift their infielders: The defense must position two infielders on each side of second base and all four infielders have to be on the infield dirt (or infield grass) as the ball is being pitched.

There will be larger bases: The size of each base will be increased to 18-inch squares instead of 15-inch squares.

Why MLB’s so confident in the changes

After years spent collecting data about what fans enjoy and would like to see improved about the sport, MLB hired former Red Sox and Cubs executive Theo Epstein in 2021 to consult on the experimentation of new rules at the minor league level. This provided the league with an opportunity to try to understand which changes work — and which don’t — before bringing them to the majors.

“At one point, I thought the panacea to fix everything in terms of making more contact for hitters was simply to move the mound further back,” one league official said. “That wasn’t feasible.”

MLB experimented with moving the mound back one foot farther from home plate in the independent Atlantic League but the results didn’t convince them to continue to examine that change at other levels. Other experiments did stick. All in all, the results of over 8,000 games played, under a variety of new rules in the minor leagues, drove how Manfred and his lieutenants arrived with the changes that will begin in 2023.

To find out if fans were in favor of the changes playing out in lower-level ballparks across the country, MLB asked 15,000 minor league fans if they supported the use of a pitch clock, broken up by how many games they attended with it in use.

The initial response to the idea was positive, and MLB found that the more games that fans experienced with it in place, the more they enjoyed it.

Their data told them that fans liked faster paced games and if the minor league results are any indication, game times could be drastically reduced in the majors this season. On average, minor league games with the pitch clock in place last year were 25 minutes shorter in 2022 than games without the clock during the 2021 season. But from time of game to the impact of any minor league experiment, the league acknowledges that baseball is entering uncharted territory and not every result will carry over.

With all that in mind, MLB officials have spent the winter preparing teams. There have been weekly calls with coaching staffs, regular meetings with managers and training for umpires in advance of the sport’s historic facelift.

Why players voted against the changes

Despite the league’s confidence, there has been skepticism throughout the process from some major league players.

A newly formed competition committee — composed of six owners, four players and an umpire — voted 7-4 in favor of the changes last September. But all four players on the committee voted against everything except bigger bases. MLBPA leadership elected not to comment for this story, noting it stands by the statement it released after the vote that said in part: Major League Baseball was unwilling to meaningfully address the areas of concern that Players raised, and as a result, Players on the Competition Committee voted unanimously against the implementation of the rules covering defensive shifts and the use of a pitch timer.

ESPN spoke to 18 players about the upcoming rule changes, and a theme emerged: They were amenable to changes, in theory, but irked by MLB’s implementation of these new rules. It was too much, too quickly — and they felt easing in some of the new rules would have been a better path to take. Many said they would have preferred to start with a longer pitch clock, and some wanted an adjustment to the shift rules instead of a full mandate deciding where players can stand on the diamond.

“Guys were a little uncomfortable with the clock, for the most part,” competition committee member and San Francisco Giants outfielder Austin Slater said. “The thing that players were most concerned about, regarding the pitch clock, was in conjunction with that fact you’re only allowed two pick-offs.

“I understand the league’s take, if you add pickoffs, you go down a slippery slope. But that’s one that’s going to take getting used to.”

Players also believe allowing pitchers only two disengagements from the rubber will impact the opponent’s running game in a dramatic way. The league countered by saying resetting the pitch clock while allowing unlimited step-offs would negate the intended purpose of a clock since pitchers could keep stepping off.

“The impact will be late in games and when you shake off signs and have to hold runners,” one veteran pitcher who played in the minors last season said. “Even with PitchCom, if you stand there and shake off, you’re going to run out of time because the clock starts the second you have the ball on the dirt. So pitchers might just stand in the grass and get their signs, I’m sure.”

Forcing a batter to be ready in the box with at least eight seconds remaining on the clock didn’t sit well with them either.

“Hitting isn’t easy,” one player said. “I need to do things at my pace, not the commissioner’s.”

The league says that making players hurry up a bit is a price they are willing to pay because fans want a better pace of play, which is something players also understand is important for the advancement of the sport.

“Players get the length part. If you play a four-hour game, we’re not getting home until midnight.” Slater said. “We feel it the most. If it’s a four-hour game, and we’re going into a day game the next day, you better believe the players aren’t happy about that.”

Despite the results of the committee’s vote, plenty of players are in favor of the rule changes. For example, the left-handed hitters ESPN talked welcome the elimination of the shift as do some of the sport’s best defensive players.

“I’m all for being in a position where I can be athletic and move a little bit more and try to make more defensive plays,” Mets shortstop Francisco Lindor said last year. “I think this is going to put us in a better position to make good plays.”

Manfred says he understands there won’t be complete agreement among players, but contends the changes are backed up by hard evidence from experimentation in the minors and fan surveys.

“The playing rule changes are really difficult to get a consensus,” Manfred said. “It can be as simple as if it’s good for hitters, it’s probably not good for pitchers.”

What to expect from here

While some players might not be immediately on board with every change, there will be no easing into the new rules at the major league level. MLB believes the sooner it applies them, the sooner everyone will adjust — because that is what it saw in the minor leagues, where pitch clock violations decreased quickly in the weeks after changes were implemented:

So starting with the first pitch of the first spring training game, the rules will be enforced to the letter of the law with the goal of getting players used to a new version of the sport as Opening Day approaches.

“Our players are great,” Manfred said. “They’re great athletes. I think they are more than capable of adjusting. The vast majority of them already have experience with these rules in the minor leagues.”

From the pace of games to the amount of action that takes place during them, Manfred’s vision is about to take hold. The commissioner is confident these changes are necessary to keep the game moving forward.

“I’d like to see a game that moves along with a brisk pace,” Manfred said. “A game that has more action in it and a game that emphasizes the athleticism of some of the greatest athletes in the world.”