NEW YORK - The Nationals have been the beneficiary of baseball’s new and controversial slide rule this season, most notably on opening day in Atlanta when Daniel Murphy convinced umpires to rule Nick Markakis out at second base for what looked to the naked eye like a clean slide but in actuality was illegal based on the sport’s new rule.

Last night, they found themselves victimized by the rule, leading to a combination of frustration, anger and mostly confusion.

“It seems like everybody’s got a different take on it,” said Jayson Werth, whose ninth-inning slide into second base was deemed illegal by umpire Jim Joyce, spoiling the Nationals’ potential rally against Mets closer Jeurys Familia. “It seems like it’s inconsistent as far as whether it’s the rule and how many times it’s been changed since the start of the season.”

The play in question: After Werth drew a leadoff walk against Familia, with the Nationals trailing 9-7 in the top of the ninth, Murphy smoked a sharp grounder to the left side of the infield. Shortstop Asdrubal Cabrera made a remarkable, backhand play on the ball and threw to second in plenty of time to get Werth, who slid into Neil Walker in an attempt to break up the double play. Walker’s throw was far too late to get Murphy at first base, but Joyce (the second base umpire) instantly called Werth for making an illegal slide, which by rule meant Murphy was out as well.

Werth’s slide wouldn’t have raised any eyebrows in past seasons, but because he slid past the bag (and couldn’t hold on with his hand) and made some contact with Walker, he violated Major League Baseball’s new rule against takeout slides.

The problem: Werth wasn’t called out for a similar slide earlier in the game, and the veteran outfielder insisted he was told at the time by third base umpire Marvin Hudson that what he wound up doing later was within the rules.

“Tonight, there were three slides at second that went past the bag,” Werth said. “After the first one, I asked Marvin. Marvin said: ‘You only have to attempt to hold the bag.’ I said: ‘Oh, you don’t have to hold the bag?’ ‘No, you only have to attempt to hold it.’ ‘Alright.’ I thought that brought some clarity to the rule. It turns out it went against me there in the ninth.

“To me, that’s a clean slide. It’s been a clean slide for over 100 years. There were no spikes involved. I was down early. The only difference between the three slides tonight that went past the bag was that there was contact on (the last one). So if the rule is just that you can’t make contact, then Major League Baseball needs to clarify that. But right now, I think it’s up to interpretation, and I feel like it changes from day to day, from series to series, and in this case from inning to inning.”

The Nationals’ biggest complaint appears to be the inconsistent nature with which the call is being made by umpires, which ultimately leads to confusion.

“I know I’ve been told like four or five different things, from different crews, about the rules,” manager Dusty Baker said. “Last time I was told it was going to be a common-sense type thing if there was no play at first base. ... I don’t know how you teach young players now to break up a double play, because there’s no such thing as breaking up a double play. ... I wish we’d get one answer on what we’re going to do with this double play thing, because it’s going to rear its ugly head in the playoffs or the World Series or something, and you hate to have a call like that decide whether you go to the World Series or you win the World Series.”

If Werth’s ninth-inning slide was ruled illegal strictly because of the fact he made contact with Walker, there is concern among players about that as well.

“I would say from a middle infielder’s perspective, it’s a little bit frustrating that it seems like the only plays that are being called lately are the ones where there’s a hit at second base and there’s contact,” Murphy said. “It seems like Major League Baseball implemented this rule to eliminate contact, yet the only time it’s called is when there is contact. So I’d say it’s frustrating, because as a middle infielder, now it’s a reviewable play that you have to maintain (your foot on) the bag. That’s now reviewable. So you have to maintain the bag on the double play, while there’s a runner coming in. And I don’t really like to get hit, so I’m probably going to jump to get out of the way. And that seems to have been deemed a legal slide now. So unless I take a hit, then it’s a double play. And I don’t like getting hit.”

Perhaps most upset last night was general manager Mike Rizzo, who reportedly got into a heated argument with Joyce outside the umpires’ clubhouse after the game.

“You blew it,” Rizzo told Joyce, according a New York Daily News reporter who witnessed the encounter and said the two wound up having to be restrained by security and other members of the umpiring crew.

Rizzo was not made available to reporters by the Nationals afterward.

Watch the controversial call here.