The Padres are proving once again baseball is truly nuts.

Never mind that tough times have slammed the lineup’s highest-salaried hitters, by far. To the rescue have come low-salaried newcomers Jackson Merrill, Luis Arraez, Jurickson Profar, Kyle Higashioka and Donovan Solano, plus a retooled Jake Cronenworth.

Stir in Old School staples — be ready to hit the fastball, smack a fat first pitch, cut down on strikeouts — and the entertainment value has soared.

“They’re playing the best baseball in all of baseball and no one knows it,” said Merv Rettenmund, one of the grateful viewers.

The coach of Padres hitters when they led the franchise-best ‘98 team past several Hall of Fame pitchers into the World Series, Rettenmund called me Saturday to talk about the Padres.

The 81-year-old downtown resident was still buzzing after seeing another laser show, leading to an 11-1 win at Fenway Park.

“This is the first time I love to watch the Pads,” Rettenmund said. “I love to watch them take their at-bats. I don’t care if they get any hits.”

Rettenmund spent four decades in professional baseball. He played in four World Series and coached in three other Fall Classics. Seared into his wiring is that the 162-game season stands as the ultimate test in team sports.

So what he said next stunned me.

“The hitting is the best I’ve ever seen from the Pads,” he said.

Better than what he saw from the ‘98 club?

“That wasn’t like this,” he said following a nine-game stretch that produced a .294 batting average, seven runs per contest and MLB’s lowest strikeout total before the Red Sox cooled the Padres off Sunday. “These guys are barreling the ball up.”

If Rettenmund sounds a little incredulous, he has plenty of company.

But he’s not searching for smoke or mirrors. Hitting fundamentals that’ve worked for decades, he said, are driving the offense’s success.

“These guys have a game plan,” he said. “They must be recognizing pitches well. They’re putting their foot down soft and early. And their eyes aren’t even moving. You have to swing with your head behind your front foot.”

Rettenmund appreciates the difficulty of what the newcomers have pulled off.

“Right now some of these guys remind me of Tony,” he said – as in Gwynn. “They’re just up there to take a nice easy swing and hit the ball hard.”

Providing a different lens, he invoked the college-basketball machine that has eliminated San Diego State in the past two NCAA men’s tournaments.

“It’s like what Charles Barkley said about UConn – ‘They’re the only team that never has to rush’ and that’s the way the Pads look at the plate,” he said.

He raved over A.J. Preller’s trade that placed Arraez, a two-time batting champion, atop the lineup in early May.

“I don’t know why in the world Miami traded him,” he said of the low-power, defensively marginal lefty, who brought to the Padres a .324 career batting average, including a .339 mark against right-handers. “He takes a lot of pressure off the big guys.”

(When the trade was announced, a big-league scout said in this space the Padres wouldn’t regret dealing any of three minor leaguers or the big-league reliever who went to Miami in the deal. So far, those players’ results strongly support that forecast. Meanwhile, the Marlins are paying all of Arraez’s salary.)

Merrill is the 21-year-old rookie who was drafted 27th out of a Maryland high school. Not even three years ago, forgoing a scholarship to Kentucky, he signed with the Padres for $800,000 less than the MLB recommendation for his draft slot.

Passing his first test this season, Merrill hammered several big-league fastballs. From there he’s improved against both fastballs and non-fastballs, posing riddles for opponents. The 6-foot-3 Merrill has drawn scouting comparisons to Rangers star Corey Seager and Orioles marvel Gunnar Henderson, a 23-year-old who won the American League’s rookie of the year award last year and has soared even higher this year.

“Merrill is legit,” Rettenmund said. “The swing is good – really good.”

Batting .325 with eight homers on first pitches, Merrill has applied a Cardinals dictum that first-year Padres manager Mike Shildt brought with him from St. Louis.

“Destroy the first pitch before it destroys you,” said the late Cardinals instructor George Kissell, whose sayings Shildt wrote down.

Not only is Merrill taking away the “get me over” first pitch from opponents, he is making it harder for them to figure him out by jumping a wide array of other pitches and showing a tighter, loftier swing.

This month he homered off an inside-black fastball from Phillies co-ace Ranger Suarez, a fellow lefty. In the recent home stand, he homered off the third consecutive secondary pitch from Bryce Wilson, a Brewers right-hander.

Profar has roasted first pitches for a .365 batting average, seven home runs and a 1.021 on-base-plus-slugging percentage. The game-winning hit he delivered June 24, over the Nationals, took extraordinary skill.

Forced by the count to swing at a slower a knee-pitch at the knees on the outside black, Profar nonetheless back-spinned the ball 384 feet for a game-winning hit at warm Petco Park. It came after the Nationals intentionally walked Arraez.

“Very hard to do,” Rettenmund said. “He’s roaring.”

Profar’s career statistics suggest a steep correction from his blazing first half wouldn’t be surprising.

Rettenmund likes what he’s seen from the 31-year-old former top Rangers prospect whose early career was marred by shoulder injuries. “It’s gonna be tough to stop him,” he said.

Preller is no doubt mulling more trades before the deadline next month.

He must decide if the Padres can contend for a World Series title. Rettenmund isn’t sure about the pitching.

But, assuming Tatis returns from a leg injury in July, as expected, he likes the offense’s chances.

“I’m excited about the way this team presents itself,” he said.

A year after the Padres saw their hitting stars and their hitting depth undermine MLB’s second-best run-prevention unit, a homegrown rookie, a journeyman signed for $1 million and a spray hitter have engineered a turnaround with assists from, among others, a backup catcher who’s slugging .620 against righties. How very baseball.