WASHINGTON — Traditional baseball wisdom suggests orthodoxy in the ninth inning. It almost certainly would have looked at high-leverage right-hander Clayton Beeter, his experience, stuff and moxie, looked again at the alternative options, and suggested that he pitch the ninth with a one-run lead over the New York Yankees.The Washington Nationals, however, have placed their faith in modern baseball. And while that conviction — held from the top of the organization down through the man who pulls the lever in the dugout — has put them a game over .500 in the middle of July, it burned them Friday night.More specifically, they believe in platoon advantages. This is why Nationals manager Blake Butera dialed the phone in the eighth, called down to bullpen coach Dustin Glant and asked lefty Matt Krook — who entered the night with 12 2/3 career big-league innings to his name, including 4 1/3 innings this season in which he had allowed seven earned runs — to start warming for the ninth as a pocket of left-handed hitters were due up.That conviction ended with left-handed hitter Jazz Chisholm Jr.’s arms spread out like a prophet’s, a baseball in the second deck at Nationals Park after Chisholm’s two-run, go-ahead homer, and Krook sauntering off the mound, wondering what the heck happened in what became a 5-3 defeat.Did the result shake Butera’s belief in the platoon splits?“Yeah, 100 percent,” he said, his voice hoarse after the game. “I mean, I’m sitting here wondering if that’s the right thing to do or not. Whenever you lose and get beat that way, you definitely question what we’re doing.”And yet?“Sitting here, talking with our group after the game tonight, we all believed the process was right and the outcome was not,” Butera said. “We have four lefties in our bullpen because we expect them to do well against left-hand hitters and particularly against this group with a heavy left-handed lineup.”The metrics were shaky. Beeter has held left-handed hitters to a .595 OPS this season. The counter was that Krook had a strong outing against Houston Astros star Yordan Alvarez on Tuesday, and held lefties to a .182 batting average against in the minor leagues this season. The other counter was who was due up for the Yankees: Cody Bellinger (who hits everyone well), Jasson Domínguez (career .589 OPS versus lefties) and Chisholm (career .658 OPS versus lefties).The Nationals will probably keep at it. They have targeted low-slot left-handed relievers over the last few weeks, noting the advantage they hold over left-handed hitters. They will continue to search for the right personnel, first across 20 rounds of the MLB Draft this weekend, then again before the Aug. 3 trade deadline. But the former is a future fix, and the latter an uncertain one.The Nationals’ left-handed relievers entered the night with a 5.03 ERA (and an MLB-worst 5.93 xERA). The team now has a 6.90 ERA in the ninth inning and beyond, by far the worst mark in MLB this season, even as Beeter’s ninth-inning ERA sits at a respectable 3.21. Chisholm’s blast was the fourth go-ahead home run they have conceded in the last 16 games, the 43rd earned run they have given up with platoon advantage in the ninth, which culminated in their MLB-worst 26th blown save.So is that darn ninth different?“I think it is,” Butera said. “And look, when you’re facing three hitters in the ninth like those three, it doesn’t help your case at all. But at the end of the day, these guys in the bullpen, they’re going to have to get big outs for us.”“The game, it matters more in the ninth inning,” Krook said. “Obviously, you’re trying to get the last three outs. So just trying to do my best to execute.”The larger question then becomes, is this one bad decision, amplified against a World Series contender in front of a sellout crowd, or is sending baseball tradition to its grave a concept that will continue to cost the Nationals?“I’ve explained it to all of them,” Butera said. “And the big thing for them is, whether they agree or not, they’re just happy that they have some clarity and understanding and what our process is and what it’s going to look like. And to be honest, we try not to deviate from it, so that these guys aren’t wondering what’s going on. They pretty much know when they’re going to be asked to pitch, when they’re asked to pinch hit, all those things.“We believe in our process.”