WASHINGTON — Watching Stephen Strasburg on the mound in 90-degree heat, Washington Nationals Manager Dusty Baker recalled how he heard the right-hander would “wilt” in these situations.

Nothing about Strasburg’s outing against the Pittsburgh Pirates on Friday night, or against any other opponent this season, has resembled wilting. Strasburg is the first National League starting pitcher to begin a season 13-0 in more than 100 years, recapturing the dominance he showed early in his career before Tommy John surgery.

Strasburg has won 16 consecutive decisions dating back to September, and during that stretch has struck out 182 batters and walked 37. This season, his 2.51 ERA is sixth in the majors, and his command of his pitches is reflected in the numbers.

“In my opinion this has been the best year I’ve seen him pitch,” catcher Wilson Ramos said through an interpreter. “He’s been very effective attacking the zone, keeping the ball down. He’s been hitting his spots very well with all his pitches. Usually a starter that attacks the zone like that and doesn’t miss his spots very much will usually (have) success like he’s been having.”

Mixing his overpowering fastball with a cutter, curveball and change-up, Strasburg has thrown an impressive 66.4 percent of his pitches for strikes, and yet batters are hitting .195 against him with only 11 home runs in 17 starts.

Perhaps the most impressive number is the zero in the loss column.

“He hasn’t lost,” Pirates Manager Clint Hurdle said. “That’s pretty hard to do up here. It’s in late July and he hasn’t lost a game. Whatever he’s doing, he’s probably going to continue it.”

Strasburg’s 13 victories to open a season are tied with teammate Max Scherzer and Ron Guidry as the sixth-longest streak in major league history and mark the longest in the NL for a starter since Rube Marquard of the New York Giants went 18-0 in 1912.

Asked if this felt like a 13-0 season, the 27-year-old didn’t know how to answer.

“The results, I can’t control,” said Strasburg, who signed a $175 million, seven-year contract extension in May. “I’m trying to go out there and execute pitches and roll with the highs and lows. It’s always going to be that way. You ask any veteran pitcher in the league, there are years where they feel like they really dominated all year and just didn’t have the numbers to show for it, and there are other years where they feel like they realty didn’t pitch to the level they expected and they had all the numbers to show for it.”

There are tangible explanations for Strasburg’s numbers, and Baker said it starts off the field. The veteran baseball man said the Nationals’ staff urged Strasburg to increase his work between starts.

After an injury-filled 2015 that included a strained left trapezius muscle, a strained oblique and other tweaks that had little to do with pitching, Strasburg changed his workout approach. He may not work out more, but he does it differently.

“As I’ve gotten older, it’s not trying to go out there and lift the house in the weight room,” Strasburg said. “I think I’ve just been trying to get back to square one, ready for the next start. Throwing that many pitches, doing that over and over again, it kind of takes a beating on your body, so we’re just trying to work with the training staff and identify what areas I need to work on to get feeling good for the next one.”

Strasburg missed two weeks this season with an upper-back strain, but that didn’t slow him down. Since returning from the disabled list July 3, he has allowed just two earned runs on five hits and struck out 20 in 212/3 innings.

Some of that dominance is mental, according to Ramos, who said Strasburg had a tendency in previous years to get down when things didn’t go his way or the defense let down. Ramos has talked to Strasburg about letting his pitches work and the defense take care of things.

“So far he’s having a great year and his attitude is, I think, the biggest difference with the way he’s going out there and just being aggressive – a lot more aggressive than he has been in the last few years, and I think that’s made a big difference,” Ramos said.