Hard-throwing Mets right-hander Jacob deGrom will get the call in Game 2 of the World Series against the Royals. (Jonathan Daniel/Getty Images)

KANSAS CITY — The defining element of the New York Mets is what we have come to expect late in October, and when the World Series begins Tuesday night, the radar gun will light up to prove it. In an era when strikeouts set new records every year, their pitching staff fits right in, built to strike hitters out. Their young rotation – the graybeard in the group is Jacob deGrom, all of 27 and in his second major league season – will push or exceed 98 mph from its first pitch to its last. This is classic Fall Classic: overwhelming velocity.

The Kansas City Royals arrive, then, from yesteryear. They’ll swing at those fastballs early in the count and drive them up the middle. When they get two strikes, they’ll – get this – choke up on the bat handle and shorten their swings. In an era when strikeouts are all but accepted by offensive teams, the Royals take their strikeouts personally – and therefore swing and miss less frequently than any team in baseball.

So we come to the Something Has To Give World Series, the try-to-hit-this power of the Mets’ pitching vs. the we’ll-hit-anything-you-throw-at-us approach of the Royals’ hitters. And it will begin with the very first hitter Tuesday night, when Mets right-hander Matt Harvey – whose fastball velocity is among the highest in the National League – faces Royals shortstop Alcides Escobar, among the toughest American League hitters to set down on strikes.

“We can’t continue running 97-mph fastballs,” Mets Manager Terry Collins said. “They’re eventually going to get to them.”

This confluence of skill and strategy comes both from God-given ability and organizational approach – on both sides. Start, though, with the Royals, because while the flame-throwing Mets have merely capitalized on the trend that has overtaken the sport, Kansas City has actively cut against it. The Royals not only strike out less frequently than any team in baseball, but it’s not close. Their strikeout rate of 15.9 percent, and their total of 973 strikeouts, were the lowest in baseball. Next: the Atlanta Braves, who struck out 1,107 times. The Chicago Cubs, in contrast, struck out 545 more times than the Royals.

“It’s a skill as much as anything,” Royals hitting coach Dale Sveum said. “You have to have guys that care about not striking out. I think you have a lot of hitters nowadays that [say], ‘What’s the difference between striking out or hitting a groundball out?’ Over the course of a season, it’s huge. It’s runs. If you strike out, you don’t have the chance of the ball hitting the outfield grass. … I never saw a strikeout go over the fence. I never saw a strikeout turn into a double.”

Part of this is born of Kansas City’s design. Kauffman Stadium measures a healthy 387 feet to the gaps. The Royals opened the season with a middle-of-the-pack payroll, slightly less than $114 million. Power is expensive, and power might not play in this ballpark. So General Manager Dayton Moore has consciously chosen to assemble a group for whom contact matters.

“Personally for me, I hate striking out,” left fielder Alex Gordon said. “If I get to two strikes, I’m going to battle as much as I can. Even if I hit a weak groundball, I feel like that’s a lot better than striking out.”

This is not cheap talk, either. One hundred sixteen major league hitters struck out at least 100 times this season. Two played for the Royals – Eric Hosmer (108) and Kendrys Morales (103). They will hunt fastballs early in the count – “If you want to be successful,” center fielder Lorenzo Cain said, “you got to hit the fastball” – and drive them.

The Mets, of course, are aware of this. Because they swept the Chicago Cubs in the National League Championship Series, their starters for Games 1 and 2 here – Harvey on Tuesday and deGrom on Wednesday – should be well-rested, ready to deal heat. Throw in rookie Noah Syndergaard, who will start Game 3, and the Mets have three of the top six starters in the NL when it comes to fastball velocity, according to data compiled by Pitchf/x: Syndergaard first at 96.5 mph, Harvey tied for fourth at 95.2 mph, deGrom sixth at 94.9 mph.

“Velocity allows you to make mistakes in the zone,” Mets second baseman Daniel Murphy said.

But as Mets veteran outfielder Michael Cuddyer said, “It’s not just velocity.” What has struck scouts and opponents about these Mets fire-ballers is their ability – and their willingness – to go to their breaking stuff both early in games and early in counts. Syndergaard, for instance, uses his fastball less than 40 percent of the time. DeGrom, who appeared to be feeling the effects of a career high in innings during his last two playoff starts, got by on a splendid mix to beat the Dodgers and then the Cubs.

“What that allows them to do is game plan against the hitters’ weaknesses,” Cuddyer said. “You see a lot of guys – especially 22, 25 years old – that throw hard that go out on the mound, and they just throw hard and stick with their strengths. These guys, they don’t have to do that because they can throw everything for strikes. … They can actually game-plan for the hitters’ weaknesses and exploit that.”

That they can do so this early in their careers is enormously encouraging for Mets fans. Harvey, deGrom, Syndergaard and Game 4 starter Steven Matz, another rookie, have combined for 156 major league starts in the regular season and playoffs. By contrast, Edinson Volquez and Johnny Cueto, who will start the first two games for the Royals, have 455 between them.

The Mets’ starters, though, have advanced so quickly because they have learned from each other as well as from staff veterans Bartolo Colon and Jon Niese, each of whom has to rely on craft over speed. But when it came time to determine the playoff starters, there was no choice: Bring the heat.

“They feed off each other,” Mets third baseman David Wright said. “It’s almost like every night’s a competition. ‘Well, Harv threw seven [innings] with one run. I want to throw eight with no runs.’ And then the next guy comes up and wants to beat him. They all watch each other’s bullpens. They all talk.”

They will talk, in the coming days, about the Royals. “We know what they’re about,” deGrom said.

Before the series, we know what each of these teams is about – essentially, opposites of each other. Something has to give. The who and the how should be fascinating to find out.