What did players learn about MLB’s new rules this spring?

Team USA pitcher Merrill Kelly said the storybook scene was just as dramatic for the players in the dugout as it was for fans watching. But he also admitted there was a thought that crept through his head.

“How are we possibly going to put a pitch clock on a situation like this?” Kelly said.

Well, we’re about to find out.

Major League Baseball’s new rules package is set for its regular-season debut Thursday when all 30 teams play their first game. For many fans, it’ll be the first time seeing the sport’s sizable list of rules changes, including a pitch clock, limits on infield shifts and bigger bases. They’ve been tested in spring exhibitions but weren’t used in the WBC.

“This is the next level — having the rules applied in games that matter,” said Diamondbacks three-time All-Star Evan Longoria. “Nobody’s getting numbers stamped on the back of a baseball card during spring training.

“I think this is going to be a huge adjustment.”

The good news for baseball is that the rules changes have been widely praised during spring training. Games move at a noticeably crisper pace: MLB says spring games averaged about 2 hours, 35 minutes through the first three weeks, 26 minutes shorter than spring games last season.

The limitations on the infield shift haven’t been a particularly big concern. The bigger bases — which could help curb collisions and injuries — have hardly been noticed.

MLB has also shown a willingness to listen to feedback from players. Last week, the commissioner’s office sent a memo trying to clarify some rules issues from spring training.

But everyone knows the real test begins Thursday.

“I think there will be a lot more gamesmanship during the regular season,” Cubs pitcher Drew Smyly said.

Some of that showed in spring training. New York Mets ace Max Scherzer and other pitchers tried weaponizing the pitch clock, hurrying hitters or waiting them out within the bounds of the 15-second timer — 20 seconds with someone on base — to mess with their timing.

“Really, the power the pitcher has now — I can totally dictate pace,” the three-time Cy Young Award winner said.

The cat-and-mouse game between pitchers and would-be base stealers will be particularly intriguing during the season’s opening weeks. Pitchers can only disengage from the rubber twice in each at-bat, meaning limited chances for pickoff attempts. If a pitcher disengages a third time and doesn’t record an out, a balk is called and all runners advance one base.

Stolen bases and stolen base attempts during spring training increased about 50% over the numbers from last year’s spring games.

And they could jump again in the regular season.

“We didn’t want to tip our hand, to be honest with you,” D-backs manager Torey Lovullo said of his team’s running strategy. “But trust me, we’re working on things behind the scenes.”

The emphasis on athleticism is at the core of what MLB wants in its 2023 games, and the sport has been aggressive in its marketing. A recent video on MLB.com — with the cheeky title “Get that shift … outta here!” — featured ‘Breaking Bad’ actor Bryan Cranston celebrating the changes.

So far, it seems players and coaches are cautiously optimistic the rule changes will be a good thing.

Los Angeles Dodgers ace Clayton Kershaw said the idea of a pitch clock was much more scary than the actual pitch clock.

“I find myself staring at it and thinking about it more than I probably need to,” the three-time NL Cy Young winner said. “As we get going into the regular season, I don’t think it will affect me.”

San Francisco Giants manager Gabe Kapler said he expects the new rules to take some of the mind games out of baseball.

“Before you could step out of the batter’s box and catch your breath, look up at the sky, take your time getting back in,” Kapler said. “The worst you would get is the umpire saying, ‘Let’s go’. Now there is a real penalty for it.

“Taking all the thoughts out of your head. I think it will be most advantageous for the athletes.”

The Ohtani vs. Trout showdown in the WBC — which ended with Ohtani striking out his Los Angeles Angels teammate to preserve a 3-2 victory for Japan — wasn’t subject to this year’s rules.

Would the pitch clock make that situation move a little more briskly? Sure.

But Lovullo — the Diamondbacks manager — said the good of the new rules outweighs the bad. He was watching the U.S. play Mexico during the WBC a few weeks ago when he felt the game dragging a little. At first, he thought it was the eighth inning.

Then he realized it was just the third.

Suddenly, a pitch clock didn’t sound so bad.

“I’ve adjusted and I think everyone’s adjusted,” Lovullo said. “I think the rules are really good.”