WEST PALM BEACH, Fla. — As a teenager in a nameless No. 91 jersey flew around first base and the baseball he hit flew toward center field, a few fans watching in the bleachers behind home plate nudged their neighbors.

“Is that him?” one asked, a little more audibly than the rest, because the kid was not on her roster. Yes, someone told her: The kid with his socks pulled high, charging around Field 6 at Ballpark of the Palm Beaches, was Victor Robles.

The kid, unremarkable as he looked in the midst of players a decade or so older, had just hit a ball harder than anyone else had in Thursday’s intrasquad game. That kid, 19 years old and playing against Nationals major leaguers for the first time in his young career, is the top prospect in their system and one of the 15 best in baseball, according to most publications.

Robles’s debut in big league camp was a subtle one, made in an unofficial game played to give pitchers such as Stephen Strasburg, Tanner Roark and Koda Glover some chances against hitters before the Grapefruit League season begins Saturday. But that he was there, in center field and batting third for Team Strasburg, showed the speed with which the dynamic Dominican is charging through this system.

Though Robles has never played a professional game above single-A, some within the organization wondered whether he might be ready to come to big league camp this spring. Ultimately, they decided against it, choosing caution over curiosity. But when the desire to preserve the regulars left the Nationals in need of a few extra bodies for Thursday’s scrimmage, Robles got an early chance.

“I felt comfortable,” Robles said through team interpreter Octavio Martinez. “That’s what I work for, to prepare myself and face big league pitchers. I felt good.”

He faced Tanner Roark, a now-proven ace who happened to be emphasizing throwing inside Thursday, in his first at-bat. Robles hit a dribbler to third base and had an easy hit, because few players in the Nationals system run like he does.

Not long after, Roark picked him off second base, having discussed that very scenario with second baseman Manny Burriss beforehand. Roark, nearly a decade into his professional career, figured the speedy youngster might be eager to run. Experience still counts for something.

Robles finished 1 for 3 with a hit, that deep fly ball to center, and no notable defensive achievements. All in all, it was a solid showing for a teenager facing big leaguers for the first time, a few yards away from where his manager, his general manager and several other front-office members sat watching.

Games such as these, when Dusty Baker and Mike Rizzo hop off stools to serve as impromptu batboys and pitchers shuffle in and out, are not serious enough to be used as the basis of lasting conclusions. But as minor leaguers years older than Robles gathered for their workouts at the next field over and peered through the chain-link dugout fence, they seemed a world away.

Strangely enough, many Nationals big leaguers and fellow prospects had not seen Robles play much before Thursday. But he is the player the Nationals refused to trade as they let fellow highly touted talents Lucas Giolito and Reynaldo Lopez go. He is the position-playing prize of a system known more for churning out pitchers and a key part of the Nationals’ plans to restock their outfield when Jayson Werth and, perhaps, Bryce Harper, no longer roam it.

“He’s so young, he’s just here to play,” Baker said. “I don’t think he’s worried about, or should worry about, how the organization feels about him. … I know he’s a focal point in the minor leagues, but we’re trying not to put too much pressure on him.”

Robles will likely get a few more chances at big league camp, as one of the many minor league players called up to supplement Grapefruit League rosters when regulars need a rest.

After reaching High-A last year, Robles could start this season there or in Class AA Harrisburg, a place from which the Nationals have occasionally pulled prospects to the majors in recent years. Still, the Nationals do not generally rush prospects like him and seem unlikely to require his services before next year at the earliest.

Unlike Harper, Strasburg, Giolito, or even Trea Turner, Robles has not been in the spotlight for long. While a rise as fast as Robles’s might seem to put him at risk for baseball’s version of the bends, the short-term effects of a rapid change in pressure seem less likely to linger than the kind of long, drawn-out build faced by other elite Nationals talents.

But as Thursday’s showing revealed, the Nationals will not be afraid to present a challenge to Robles, who has risen to every one. His answers for reporters were short but certain. One reporter asked him how he would react if the Nationals called this season, and Robles cracked a smile long before Martinez provided what seemed to be an unnecessary translation.

“I’m always ready,” he said, and so far, through three fast-moving professional seasons and one day of big league camp, he has been.

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