Shawn Kelley is struggling, and can’t seem to find any answers. (Jonathan Newton/The Washington Post)

When he arrived at Nationals Park on Saturday afternoon, a few hours after allowing his 12th home run in 23 2/3 innings, Shawn Kelley headed to the video room. He looked up all the new data the Nationals track — things like spin rate, velocity, extension, release point — hoping to find answers for his 7.99 ERA, more than four full runs higher than his career norm. He didn’t find any.

“The data is still trending upward. I’m getting back to form,” Kelley said. “I was like, that makes sense because yesterday warming up, it was a good situation — not a save, but a good chance to finish out the game, celebrate. Warming up I’m feeling great. Then it’s just like boom, boom, boom.”

With a four-run lead over the Phillies Friday night, Dusty Baker chose Kelley, instead of his closer, to pitch the ninth. Kelley hadn’t allowed a run in his last four outings, and was finally looking like the guy who served as the primary set-up man for the division-winning 2016 team. A near-save situation, instead of the blowout work he was getting, could allow Kelley to rediscover some of that late-inning swagger, Baker thought. Two hits and a home run later, Baker was calling Sean Doolittle in from the bullpen to close out a one-run game.

“I remember they called down, they said ‘hey, if we score, you’re in.’ We scored the run. I remember thinking, ‘okay, this is another good chance to get out there and get back in a situation I’ve been pitching in the last few years,” Kelley said. ” … Then all of a sudden I’m sitting in the dugout trying to cheer on Sean, but I’m scratching my head thinking ‘what just happened?’ ”

Kelley has been scratching his head all season. He first landed on the disabled list in May with a lower back strain. By that time, he had allowed five home runs in 10 innings, but was striking out 11.7 men per nine innings and had converted all three of his save opportunities. Perhaps the back was to blame.

He made 11 appearances after returning from that injury, and allowed 18 runners in eight innings in those appearances, which came during May and June. In mid-June, he hit the disabled list again, this time with a right trapezius strain, which basically caused him general upper back tightness and neck discomfort.

He rehabbed from that injury, a process that took two months and required a rehab assignment that lasted eight games — about seven games more than Kelley felt he needed. Once the pain in his neck subsided, he hoped his struggles would, too. So by the time the Nationals deemed him ready, Kelley was more than eager to return.

Kelley knew he would have to work his way back into high-leverage innings, and after allowing two homers in his first three appearances back, he compiled four scoreless appearances in mostly mop-up duty. Baker saw enough to give him a more important inning Friday. Kelley thought he was ready for it. Then, he allowed another home run, and walked off the field to boos from fans who do not become unfriendly often.

“I’m too dumb to let it really bother me I guess,” said Kelley, whose teammates would not describe him that way at all. “All the signs were like, this is gonna be great. That’s the thing …”

If Kelley were hurt, like earlier this season, poor results would make sense. He is not hurt anymore, he says, which is why the whole thing is so “puzzling.” If his stuff weren’t lively, or his slider not biting, perhaps he could understand. But Kelley said he has succeeded with worse stuff than this before.

“My mechanics are simple. My slider is sharp … There’s probably another mile or two an hour I can still get back, a little bit more life,” Kelley said. “But you don’t pitch at that every time you throw as a reliever, and you still have success. So it’s just like I don’t know. It’s like baseball’s trying to tell me something.”

Whatever Kelley thinks that message is, he doesn’t show it. Since he signed here before the 2016 season, Kelley has been a positive presence in the clubhouse, a veteran adviser to younger relievers, even-keeled enough to help others do the same, outspoken enough to add some levity when needed. Even Saturday, after another agonizing outing, he joked and smiled.

“Louisville just won,” he said with a smile, after his beloved football Cardinals wrapped up their game. “So I’m okay. Otherwise, I might not want to talk about this.”

But Kelley has always been willing to talk about it, which is expected of veterans but nevertheless more easily required than done. His won’t-hide attitude has earned him respect of those around him, so much so that instead of annoyance or frustration about Kelley’s struggles, Baker spoke as if aching for him.

“We’re going to continue to try to give him some confidence, but I don’t care who you are, everybody’s human. I’ve been through it. You hear the fans hooting on you,” Baker said. “Heck, I was even one time in L.A. when I first got there right after the trade, I didn’t even want to go out of the house. I’d go to a grocery store or a bar and people would say something smart. But you have to be strong. You gotta make yourself immune to any of that, and think about your past. That’s all you really have, the good times in your past.”

Kelley has plenty of those good times, which is why these struggles — particularly, the home run struggles — are so mystifying. The highest home runs per nine ratio of Kelley’s career is 1.8, which came during his rookie season in 2009. His career HR/9 average is 1.4. This year, his ratio is 4.6. For reference, no major league reliever has ever finished a full season of work with a ratio higher than 4.5.

Because of his struggles, Kelley is no longer a lock to make the postseason roster like he was last season. Assume the Nationals carry four starters and nine relievers in the first round. Sean Doolittle, Ryan Madson, and Brandon Kintzler are locks. Matt Albers, Oliver Perez, and Enny Romero seem likely to make it, too. That leaves Joe Blanton, Sammy Solis, Edwin Jackson, Matt Grace and Kelley in the mix for a roster spot.

Jackson can provide length, if needed. Grace has pitched well enough to earn consideration, though he would give the Nationals five lefties in the bullpen. Either way, Kelley is not assured of a spot, and might miss out if his home run troubles continue.

“We’re about to clinch. It’s like, I feel good physically, There’s a lot of positives to look at,” Kelley said. “But if I want to Google myself it’s probably not very positive. If I want to read what people are saying on the Internet, it’s probably not very positive. But I don’t do that. So right now, it’s just — I don’t know.”

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