Off the bat, the ball Ian Desmond hit in the bottom of the fifth inning Friday did not look, act or seem like a home run. It behaved, in all manners, like a double — scooting on a line, then hopping toward the left field corner.

So in that manner, the Washington Nationals were robbed of exactly nothing in what became a 2-1 loss to the Atlanta Braves in their home opener at Nationals Park. When the game resumed, Desmond stood on second. He just took a circuitous route to get there.

Here is how, in 2014, a double becomes a home run and then turns back into a double. The ball Desmond hit eventually stopped in that left field corner — perhaps stuck, perhaps just stopped, under the padding on the left field wall. Braves left fielder Justin Upton threw his hands in the air. The umpires signaled nothing. Desmond kept running.

“No one said anything,” Desmond said. “So I wasn’t going to stop.”

Braves shortstop Andrelton Simmons ran toward left, screaming.

A baseball veteran who knows no other life than the grind of the sport, third baseman Ryan Zimmerman has been with the Nationals since they came to Washington. He takes a pause during spring training to talk about the mental and physical challenges of the game. (Whitney Leaming/The Washington Post)

“Simmons was panicking, telling me to throw the ball,” Upton said. “So I picked it up and threw it.”

No one knows what was going on in the minds of the umpiring crew at that moment, but there is a backdrop to this major league season, and it is that the umpires now have a backup system. There is, in all sorts of potentially controversial cases, instant replay. So here, in the bottom of the fifth inning of the fourth game of the season — a game the Nationals trailed, 1-0 — came Washington’s first truly meaningful interaction with the new system. Ever.

Braves Manager Fredi Gonzalez couldn’t even see Upton, tucked in the corner, out of sight from the Atlanta dugout. But he came out onto the field, and third baseman Chris Johnson told him Upton had raised his hands. Upton, in turn, told Gonzalez that the ball had lodged under the padding.

“I was going to challenge it,” Gonzalez said. So he did. And from there, the evaluation of the play moved from a baseball field in Southeast Washington to a video room in midtown Manhattan, where real-life umpires will make these rulings all year long.

The idea of replay is, of course, to eliminate human error, the kind that is inevitable if relying on only the naked eyes of four umpires at every game. For years, baseball has been perhaps the best officiated of all major sports. And yet, calls are missed and games are lost because of it. This is, then, progress.

But officiating, even in slo-mo, involves judgments, and judgments are debatable. The judgment Friday, after a five-minute argument-and-review, was that Desmond — who ran all the way home, allowing the Nationals to trick themselves into thinking they had tied the game — would be awarded a double.

“You hear about 10 different theories of what it could have been,” Nationals first baseman Adam LaRoche said. “I still don’t know what was right.”

The rule consulted in this instance, number 7.05(f) in your official major league rulebook, is essentially the one that governs ground-rule or “automatic” doubles. It reads like this: A player is awarded two bases if “a fair ball bounces or is deflected into the stands outside the first or third base foul lines; or if it goes through or under a field fence, or through or under a scoreboard, or through or under shrubbery or vines on the fence; or if it sticks in such fence, scoreboard, shrubbery or vines”.

Sort through that for a bit, and there are only two possibilities that would apply here. Did this ball go “through or under a field fence”? Well, kind of under one, but not like it found a hole and got to a spot on the other side, where Upton couldn’t retrieve it. Does that apply?

And if not, then did it “stick in such fence, scoreboard, shrubbery or vines”? That’s where there is debate, debate that replay had not resolved long after the game.

Upton threw up his hands, exactly what outfielders are taught to do in such a situation — a signal that they are helpless, that there’s no way they could extract the ball from where it lodged. But the Nationals, after the game, threw up their hands — if quietly. For one, third base umpire Marvin Hudson never raised his hands, killing the play.

“He didn’t make a call,” Nationals Manager Matt Williams said. “For me, in the heat of the moment and with my naked eye, it tells me that he didn’t think it was lodged underneath the fence.”

Hudson told Upton that he was on his way to check. But with Desmond running, and Simmons pleading, he grabbed the ball. One National said afterward that the fact Upton picked up the ball so easily showed that it wasn’t, in fact, “stuck” under the fence, that it should have been live.

Indeed, the ruling on the field — or, perhaps, the absence of a ruling on the field — was that it was live, that Desmond had scored. Were the umpires, in fact, allowing the play to extend because they knew they had replay upon which to fall back? We won’t know, because umpires aren’t allowed to discuss replay decisions — decisions made by off-field umpires in New York — with the media.

But crew chief Jim Joyce told Williams that the replay showed the ball was “lodged underneath, between the pad and the dirt,” Williams said.

“I questioned it with Jim,” Williams said, “because when [Upton] had to, he reached down, picked it up and threw it in.”

What, then, have we learned? Joyce, for what it’s worth, was heading to Williams’s office long after the game, ostensibly for further discussion. Gonzalez was the manager who benefitted from the new system Friday. But does he like it?

“Ask me in another month or so,” he said.

Try a full season, or more. Baseball calls — ball or strike, safe or out, double or homer – have always involved some measure of judgment. Even a Manhattan bunker full of televisions and direct, secure lines to every big league park won’t change that.