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Something isn’t right with Stephen Strasburg. Seven starts into the season, his earned run average sits at 6.06. He has pitched past the sixth inning only once. His past two starts, including Tuesday’s clunker, were shorter than four innings. His pitches don’t have the same effect on hitters as they have had in the past. A sprained left ankle in spring training appears to have had lingering effects on his mechanics.

Strasburg gave up eight hits and a career-high eight runs in Tuesday’s 14-6 loss to the Arizona Diamondbacks. The right-hander lasted only 3 1/3 innings, pulled for rookie left-hander Sammy Solis once the Nationals trailed by six runs. He trudged off the mound, headed to the dugout to watch the rest of a miserable loss and contemplate his career-worst slump.

“I’m just embarrassed I let the team down,” he said, hands jammed in his pockets and a somber look on his face. “It sucks. I’m just trying to go out there and help this team win some games. I didn’t do that tonight. I’ve just got to turn the page and get back on it tomorrow.”

What led Strasburg to this point? He missed only one spring training start because of the ankle, but he and the Nationals believe he changed his mechanics because of it, leading to the discomfort in his back and shoulder in his previous start. A visit to a chiropractor between starts helped.

After Tuesday’s start, Strasburg said his back was “good enough.” He said his back didn’t bother him on the mound but said: “I’ve just got to go out there and make better pitches.”

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“The fact that he got through it and felt good physically is good,” added Nationals Manager Matt Williams.

In between starts, pitching coach Steve McCatty watched video of Strasburg’s games and worked with him to ensure his mechanics were sound. The mechanical tweak was only a matter of inches. When Strasburg’s front foot — the previously troublesome ankle — lands shorter than normal, he throws across his body and elevates his pitches. Pitching down and away help neutralize right-handed batters.

Against the Diamondbacks, Strasburg fought through his mechanics — and lost. He left pitches up the zone, his fastballs were flat and his off-speed pitches hung. Last season, opponents hit .285 against his fastball, .155 against his change-up and .215 against his curveball. Entering Tuesday’s game, the numbers were starker: .310 against his fastball, .250 on the change-up and .316 against his curveball. Strasburg has allowed only three home runs and has a 35 to 11 strikeout-to-walk ratio in 35 1/3 innings, but he is allowing a fair amount of contact.

“I left a lot of pitches up,” Strasburg said. “I didn’t hit a spot. They’re a good hitting team. I’ve got to do better. . . . Just keep my head down, keep working hard, keep battling, keep fighting.”

Asked to pinpoint a reason for his struggles, Strasburg said he was trying to figure it out. “Wouldn’t happen if I knew what it was,” he said.

After a walk to Paul Goldschmidt and a single by David Peralta, a high fastball to Aaron Hill led to a two-run double in the first inning. A 95-mph fastball over the plate to Ender Inciarte in the third resulted in a solo home run. Strasburg struggled even more in the fourth, when the Diamondbacks scored five runs to put the game out of reach.

Strasburg fired pitches over the heart of the plate, and the Diamondbacks mashed them for hits. A fielding error by Strasburg on Diamondbacks starter Rubby De La Rosa’s bunt led to more trouble. After an Inciarte sacrifice fly scored a run, Mark Trumbo hammered a hanging slider to left field for a three-run home run. The slider, which was scrapped early last season, has curiously re-emerged, another pitch Strasburg has turned to when others have been inconsistent.

“I saw him in the bullpen,” catcher Wilson Ramos said. “He was throwing every pitch well. I don’t know what happened. It was really different on the mound than the bullpen. In the bullpen, he throw good sliders, curveballs. I say, ‘Today probably is a good game.’ I don’t know what changed his mind.”

While Strasburg could offer little explanation now for his struggles, Ramos offered one possibility.

“I think he’s thinking too much,” he said. “In this game, when you’re thinking too much, it’s hard to do everything right. For example, when a hitter goes to the plate thinking too much, you’re not going to hit the ball hard. It happens, too, with pitchers. He has to go out there and fight and try to do the best he can. You can go out there and think too much.”

After Strasburg was pulled in the fourth inning, the Nationals bullpen did only a little better. Pitching in front of his hometown crowd, Solis allowed four runs in two innings. Matt Grace allowed two more. Aaron Barrett tossed a scoreless seventh, which paved the way for outfielder-first baseman Clint Robinson to pitch the eighth to save the rest of the bullpen.

Robinson tossed a scoreless frame on nine pitches, surrendering a hit but striking out Hill. Robinson became the first position player in Nationals history to pitch in a game. Bryce Harper’s two-run home run in the sixth inning was impressive because he flailed at an outside pitch and hit it out, but it could make only a minor dent in the Nationals’ deficit.

The Nationals still believe Strasburg is a standout pitcher. His 3.10 ERA from 2012 to 2014 is 14th best among all starters. His 10.17 strikeout-per-nine-inning rate is third best in that span. He just has yet to take the next big step in his career many dreamed he would make and he is now mired in a skid.

“He’s got great stuff,” Williams said. “His stuff will show itself in the end. We’ve got all the confidence in the world in him. It hasn’t been his best stretch but he’s a competitor and goes out there every fifth day . . . and goes at ‘em. The concern coming out of the last one was his health and I think he passed that hurdle. So now he’ll get back in the swing of it.”