Stephen Strasburg confers with catcher Wilson Ramos in the fourth inning after a miscommunication that led to Paul Goldschmidt’s game-tying hit. An inning later, Goldschmidt would tag Strasburg again. (Matt York/Associated Press)

Of the 98 pitches Stephen Strasburg threw against the Arizona Diamondbacks on Tuesday night, there were two that stuck out the most. Locked in a duel with Diamondbacks starter Bronson Arroyo, with scoring at a premium, the Nationals starter had little room for mistakes.

But Strasburg made a pair of game-altering miscues. In the fourth, he threw a high fastball to Miguel Montero that the Diamondbacks catcher lined to center to score Paul Goldschmidt, who had doubled to open the inning. Ramos called a change-up, but Strasburg read the sign for a fastball. The miscue led to a single that tied the game at 1.

An inning later, Goldschmidt hit a hanging Strasburg curveball to deep right-center for a two-run double that put the Nationals in a two-run hole that they couldn’t recover from in a 3-1 loss. Strasburg fired scoreless innings in the sixth and seventh, but the Nationals lineup could bring no runners home against Arroyo. Instead, the Nationals and Strasburg were saddled with the loss.

“Just two pitches,” Ramos said. “Nobody’s perfect. How many pitches did he throw? 100? 100-something? That’s a lot. He missed two. Nothing bad I can say.”

Strasburg has had difficulty in the first innings of his starts, yet has been dominant afterward. So when he breezed through the first three batters he faced on seven pitches, he looked poised for a strong start. And for much of his start against the Diamondbacks, Strasburg was exactly what the Nationals have come to expect.

It’s still early, but the Nationals have committed the third-most errors in baseball. The Post Sports Live crew looks at whether a team with poor fielding can still realistically win the division. (Post Sports Live/The Washington Post)

In the fourth, however, came the first hiccup. He allowed Goldschmidt, one of baseball’s best hitters, a leadoff double. Then came Montero. Strasburg and Ramos miscommunicated on the pitch to Montero, and the pair convened on the mound after the game-tying hit. After the game, Ramos vowed to use colored stickers on his fingernails next time to make sure pitchers see his signals.

But Strasburg’s biggest blip was an inning later, and the mistake was entirely his own. He surrendered a leadoff hit to Arroyo, his second of the night. A one-out single by Martin Prado tightened the screws with Goldschmidt stepping in.

Strasburg fell behind 2-0 before bringing the count back to 2-2. Strasburg wanted to throw a curveball lower in the strike zone but instead, he said, the conditions were a little windy and dry and the ball spun out of his hand.

“As soon as it came out, I knew it probably wasn’t going to be good,” Strasburg said.

Pitching from behind, Strasburg adjusted and gave the Nationals two more scoreless innings. He took the mound in the seventh, trailing by two runs and with his pitch count sitting at 88, and he induced three more outs. He left the bullpen with only one more inning to cover, but his mistakes in the earlier innings put the Nationals in a tough position.

“The biggest thing is keep it close,” Strasburg said. “Keep us within one or two runs. I feel like I threw a lot of strikes [Tuesday]. Arroyo just pitched better. Definitely feel like I had enough in the tank to go the distance.”

Arroyo, a 37-year-old right-hander with a sinking fastball that topped out around 87 mph, carved through the Nationals. He kept hitters off balance with his array of varying speeds, breaking balls and arm angles.

“It’s hard when you’re predominantly right-handed,” Manager Matt Williams said. “He can throw all of his pitches for strikes. Multiple arm angles. It’s difficult.”

The Nationals struck first because of the breakthrough of a scuffling hitter. Ian Desmond entered the game hitting .218 with a team-leading 44 strikeouts. In the second inning, Desmond waited on an 87 mph sinker and drilled it to right field. Ramos chugged around the bases and Desmond slide safely into third base for an RBI triple.

The Nationals squandered two notable scoring opportunities against Arroyo. In the fifth inning, with Tyler Moore on third base and Kevin Frandsen on first base with one out, Williams called for a safety squeeze with Strasburg at the plate. Strasburg bunted the ball back to Arroyo and only Frandsen could advance. Denard Span then came to bat with runners at second and third with two out, and proceeded to strike out.

“If he lays down a good bunt to the right side, Tyler’s going to break from third, though,” Williams said. . . . But the ball was bunted right back to Arroyo. So there was no chance for Tyler to score.”

“I wish it could have been to the first baseman so we could have scored,” Moore added. “We had our opportunities but we didn’t capitalize.”

The Nationals had another chance to break Arroyo in the eighth inning with one of their best hitters at the plate. After a pair of singles, Anthony Rendon stood at first base and Nate McLouth at second. Jayson Werth came to the plate with two outs to face Arroyo, with one hit in three previous at-bats against him. But Werth got under an Arroyo side-arm slider and flied out to left field, tossing his bat into the ground in disgust as he ran to first base.

“I saw it good and felt like I was on it,” Werth said. “It was up and wasn’t a total hanger. It was a pitch I could have and should have done damage with. It’s a game of inches sometimes and I just missed it and felt like that was the difference in the game.”

Arroyo took the mound in the ninth inning with a pitch count at 100 and an appreciative crowd behind him, and he sat down the three batters he faced. The Nationals retreated to the dugout as a team only one game above .500 and with six weeks of inconsistent play.

“Everyone isn’t looking at it like a bad thing to be playing above .500 ball right now,” Werth said. “Especially if you believe we’re the type of team that is going to get hot and make a run at it. We need to keep our head above water right now with all the guys out and start to get some guys back and need to be in striking distance when you get to the second half. We’re fine. We’re more than fine.”