Nationals shortstop prospect Carter Kieboom makes a throw for the U.S. team during Sunday’s Futures Game at Nationals Park. (Patrick Mcdermott/Getty Images)

When a huge crane appears a few blocks outside Nationals Park, even if it stands above an empty hole in the ground, it is usually a symbol of the future. A new building will change the skyline in that spot, in a year or two at the most.

When a minor league player appears in the Futures Game, he also is a symbol of the future. A young player, a possible star, is about to change the baseball skyline of his town. And the time frame is often the same — a year or two.

That’s why the appearance of 6-foot-2, 190-pound shortstop Carter Kieboom in this prestigious game is a stake in the ground for the Washington Nationals. Kieboom, 20, is hitting .305 since being called up to Class AA Harrisburg and projects to be the Nationals’ next second baseman after gimpy Daniel Murphy, who’s in his walk year, departs.

Whether Kieboom merits a September call-up, then a chance to win a starting job out of spring training in 2019, or follows a more standard path with Class AAA ball next year and a prominent role for the big club in 2020 will be left to his bat to decide. So far, that bat seems to be in a hurry.

Kieboom already has shown the kind of monotonously excellent offensive stats in five different leagues that talent evaluators love. He’s the same everywhere he goes — a batting average of about .300 with power, walks and an on-base-plus-slugging percentage around .860 — as if the competition is not defining his performance nearly as much as his talent and his ability to adapt to better foes is letting him maintain the same performance.

Such minor league numbers hint at a future player who could play middle infield early in his career but also move to third base with offensive production that might resemble Trea Turner or Anthony Rendon.

However, Kieboom’s quick advance since he was drafted in the first round (28th overall) out of high school in 2016 with a $2 million bonus also has given the Nats difficult options at an important, perhaps even desperate, juncture in their season.

Everybody wants Kieboom. He’s rangy, has power and eventually will play multiple positions. He’s about as certain a solid big leaguer as you will find yet unlikely to be a future superstar that you would regret losing forever. Should he be traded before the July 31 deadline? Six weeks ago, that would have been ridiculous. The Nats seemed fundamentally stable, sure to get healthier, play better and make rookie Manager Dave Martinez seem less at sea.

But after playing ugly 11-22 baseball for more than five weeks, full of slipshod mistakes, bad base running, poor situational hitting, short starts by their rotation, managerial head-shakers and even a lack of hustle by stars such as Bryce Harper, the embarrassed Nats find themselves at .500. Although they are “only” ­5½  games out of the National League East lead, do they need a shock trade?

With outfielders Juan Soto, 19, and Victor Robles, 21, viewed as untouchable, would either Kieboom or 18-year-old shortstop prospect Luis Garcia, the youngest player in Sunday’s Futures Game at Nationals Park, be part of a deal?

The Nats always have been such long-term planners that you would guess not. Yet with five key players set to leave in free agency, including Harper, Gio Gonzalez, Matt Wieters and Ryan Madson, 2018 would be a terrible window to waste.

If no big move is made, part of the reason may be that the Nats view Kieboom as integral to their future as Soto and Robles.

Kieboom’s appearance here seems a bit like a fairy tale since his older brother, Spencer, the Nats’ backup catcher, has a locker directly across the clubhouse from where Carter dressed Sunday. “Where is it?” he asked since he had never been in the Nats’ room before and seen only one game here.

“Look at it. It’s awesome,” Kieboom said of the clubhouse. “It’s something every baseball player dreams about, to be in a locker room like this one day. Bright lights, nice lockers. It’s clean. It’s spotless. Everything is cleaned for you. It’s great food, and it’s, well, awesome.”

Kieboom grins at how silly this sounds because everybody listening to him knows how gritty and miserable, in relative terms, the minors are.

“Famous line in pro baseball,” Kieboom said of bush leaguers who don’t relish their subsistence-level accommodations. “If you don’t like it, play better.

“That’s all I can do. Just play every day and hopefully one day I’ll be up here for a while.” Or more likely a long time.

It helps to be at the right place — or at the right positions — at the right time. The Nats are going to need a second baseman in 2019 or a third baseman in 2020 if Rendon leaves as a free agent, and Kieboom will have a shot at both jobs.

This year, in 81 games at Potomac (high A) and Hagerstown (Class AA), exactly half of a theoretical 162-game season, Kieboom has hit .300 with a .379 on-base percentage and a .480 slugging percentage and has compiled 60 runs, 53 RBI, 20 doubles, 13 homers and seven steals. For his three minor league years combined, he has slashed .288/.374/.479. All these numbers may look like gibberish except for one vital factor: what Turner, Harper, Ryan Zimmerman, Rendon and many others slashed in the minors was a fine predictor of the players they became.

The big leagues cool you off — sometimes not much, like Harper and Turner. Sometimes 100 OPS points, like Zimmerman and Rendon. But if you have trouble hitting in the minors, like Wilmer Difo or Pedro Severino, you will hit even less in the majors. If you torch the minors, like Soto, then that may carry over, too.

On Sunday, Kieboom made an excellent ranging stop of a grounder behind second base and fanned in his two at- bats. Each time he came to the plate, he was greeted by chants of “Let’s go, Nats” and “Let’s go, Carter” by a crowd that already knows his potential.

The way to bet is that those fans will get to see his fine future play out in front of them. Unless the Nats think that what ails them is truly serious, even toxic to their season, in which case something as bright and shiny as Kieboom might be the painful price of fresh energy and hope.

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