The delay only added to the mystique, like a sonic boom rumbling across the sky five seconds after a fighter jet soars past.

Josh Donaldson was pouncing on batting practice pitches Thursday, driving them with shocking savagery toward the center field fence, then resetting his stance to await another. And as the obliging coach wound up to deliver, a loud “clang” would ring out, the sound of the previous ball crashing into the corrugated metal batter’s eye.

Four times it happened in one session of BP, a power performance so remarkable, the training camp spectators gathered on the back field erupted into applause as Donaldson finished.

“That was cute,” the newest Twin said of the unusual ovation.

“People love bombs,” Eddie Rosario agreed, suitably impressed.

It’s not just Donaldson’s home runs that have captivated fans at Twins spring camp, though; it’s the way he generates them. Donaldson has one of the most recognizable swings in the major leagues, a kick-and-explode style that might remind a few Minnesotans of a certain Hall of Famer on the Twins’ two world championship teams.

“Kirby [Puckett] had that big kick — you knew right away who it was if you saw it,” Torii Hunter said. “It couldn’t be anyone else.”

Nor could this leg kick belong to anyone but Donaldson, who adopted the device as his professional career seemed to be fizzling, and soon became one of the most feared hitters in the game.

“I got sent down [to the minor leagues] five times. The most homers I ever hit in the minors was 18. Now you look at my major league career, I’ve hit 41 homers, I’ve hit over 200 homers, I’ve had a substantial big-league career,” said the 34-year-old Donaldson, who the Twins deemed worth a $92 million commitment over the next four seasons. “To me, the benefits of understanding the whys and the hows of my swing took me to that.”

Smooth move

Donaldson begins his swing by pulling his front leg toward his abdomen, his left foot raising parallel to his right knee, which momentarily shifts his weight onto his back leg. Then he rhythmically stretches his left foot forward and plants it on the ground, his toes pointing at the pitcher. That triggers another much larger weight shift forward, his hips torquing explosively toward the ball while pulling his hands smoothly ahead, the bat passing through the strike zone.

When he makes square contact, the ball jumps off his bat so quickly, it seems an illusion. Yet to Donaldson, the swing should feel almost effortless.

“There’s a science behind it,” Donaldson said. “You hear people say they try to [swing] 100 percent. I don’t want to go 100 percent. I want the ability to go 100 percent, but I want it to feel 70 percent. I want it to feel easy.”

He likens the result, the impact, to a golf shot, the way professional golfers crush drives impossible distances yet swing with more fluidity than violence.

It has other benefits, too.

“He uses the ground very well. He generates so much force from his lower half,” Twins co-hitting coach Edgar Varela said. “Leg kicks are a timing device, and he’s mastered this one for himself.”

That doesn’t mean Donaldson uses it to time the pitcher’s motion, however.

“He’s not moving based on where the pitcher’s hand is, or something like that, not directly. He has a different purpose,” said Michael Cuddyer, a former leg-kick proponent himself, who has worked with Donaldson this spring. “He uses the leg kick for his own internal timing of getting the swing started. His swing is a sequence, and that’s just the trigger.”

‘Where’s my foot?’

For all the attention it attracts, however, Donaldson downplays the leg kick’s importance. He has worked to perfect his entire swing sequence, and has a broad understanding of the physiology of his mechanics. Starting with a leg kick is simply a mechanism that is most comfortable for him, Donaldson said, but it’s not the reason he’s successful.

“It’s a style of hitting, but there are lots of different styles that work. Those aren’t fundamentals of hitting,” Donaldson said. “It’s important to know the difference. I definitely think the leg kick helps me to generate force, but I adapted it just because it was more natural for me.”

The thing is, it’s not a natural style for all hitters, or even many. Byron Buxton found that out three years ago, for instance, when searching for something to rejuvenate an inconsistent career. The Twins center fielder was encouraged to adopt a leg kick, but it was the opposite of natural for him.

“I’m not going to say you can’t learn it, but it’s a lot harder to do that at this level. Me, it made me think too much in the batter’s box,” said Buxton, who abandoned the approach after about 16 months of trying it. “With that leg kick, I’m thinking, ‘Fastball, go quick.’ But then if it’s an offspeed [pitch], and I’m not making good contact. So you end up always guessing. ‘Man, I hope he throws me a slider here.’ That’s another reason why I had to get away from it. Think, think, think. ‘Where’s my foot, how fast do I put it down?’ ”

That’s why Buxton has marveled at his new teammate’s kick. “The most impressive part is, it doesn’t matter how quick or how slow a pitcher is to the plate, his timing always looks the same,” Buxton said. “If a pitcher threw quick, I would rush and get off-balance. But he’s still on it. It’s kind of crazy.”

On deck

The Twins have another leg-kicker who may be in Minnesota soon. Top prospect Royce Lewis has utilized an exaggerated kick for much of his life, and still does — even though he’s had to fight to keep it.

“In high school, when I was 14 or 15, I saw [former big leaguer] Hanley Ramirez hit a home run with a big kick, and I thought that’s how you generate power. That’s not really the case, but it’s how I’m comfortable swinging. It feels natural to me,” Lewis said.

But when Lewis hit a slump last season, he discovered a couple of truths about baseball: Everybody is an amateur hitting coach. And because the leg kick is unusual, it must be bad.

“That’s always the first thing everyone thinks of because it stands out. And I had all kinds of people telling me, ditch the leg kick, make it shorter, this or that,” Lewis said. “But it’s not the reason. I have a good base and a routine, and I know the fundamentals. My foot gets down, and it’s just how I get into position.”

Rod Carew’s iconic batting stance — leaning over the plate, his weight shifting back and forth on his feet — was about as diametrically opposite from Donaldson’s leg kick as a stance can be. But that doesn’t mean the Hall of Fame can’t appreciate the technique.

“It’s about being in balance, and he’s got very good balance,” Carew, the 1977 AL MVP, assessed of the 2015 AL MVP. “You look at him at the top of his kick — everything is centered. He has all his weight balanced, and then he lets it all go forward. It’s very effective.”