Blake Treinen. (AP Photo/Paul Beaty)

Blake Treinen has bounced between the major leagues and Class AAA Syracuse four times this season, including his spot start in the second game of Saturday’s doubleheader in Chicago. The back and forth poses certain challenges — frequent travel, often last-minute, and changes to his pitching schedule — but Treinen isn’t complaining. When the Nationals have needed an extra arm and starter this season, he has been their top choice, with injuries to other depth helping his chances, too.

“You can’t be upset even if it’s a spot start,” Treinen said. “It’s the big leagues, what everyone dreams to do. I kind of know my role this year, which is whatever they ask me on any given day and I’m okay with that. Ideally, everyone wants to be here long-term. But right now, I understand my role is to help out when they need it and I’m okay with that. I just try my best to prepare myself and give the team a chance to win.”

Treinen, who filled in for injured Gio Gonzalez earlier in the season, heard rumors about his potential spot start and that he would be called up as the 26th man for the doubleheader, but Manager Matt Williams didn’t announce it officially until Wednesday. He joined the Nationals for Saturday, and Saturday only, and again showed that he is a potent arm and a valuable part of their depth.

Treinen fired five innings against the Cubs, allowing two runs on one swing, a home run by Luis Valbuena in the fourth inning before the rain came. He struck out three Cubs, walked only one and induced nine groundballs. And even though he had a 2.08 ERA and pitched well in his previous four starts — all doomed by a few mistakes and lack of scoring — he finally earned his first major league win on Saturday.

“It was kind of a bizarre game with the rain delay,” Treinen said. “I’m glad I was just able to go five, I guess. It feels great. But realistically, at the end of the day, did you give the team a chance to win?”

Before Treinen could do that, he had to endure the first rain delay of his young career, a 55-minute stoppage with two outs in the fourth inning. He also had to deal with Wrigley Field, a historic but antiquated stadium. Because there is no covered bullpen and the batting cages are behind the outfield wall, Treinen was limited in his ability to warm up after the delay. At Nationals Park, like most major league stadiums, there are indoor batting cages where Treinen would have thrown every 10 minutes to stay warm.

Instead, Treinen sat in the dugout with Williams and pitching coach Steve McCatty, and then warmed up in the outdoor bullpen once the end of the delay neared. In other words, Treinen sat for a long time.

“It’s hard when you’re the starting pitcher and you’re not used to stuff like that,” Williams said.

Treinen returned in the bottom of the fourth inning and his normally 95-mph sinker dropped to 92, a result of the rest. He struck out Nate Schierholtz and then pitched the fifth inning, his velocity still a tad lower than normal. And once through the fifth, Treinen was in line for the win and Williams turned the game over to the bullpen.

During the start, Treinen flashed a pitch he has been working on at Syracuse. He throws primarily sinkers to get groundouts, but to survive in the majors in the second and third time through a lineup, his offspeed pitches are needed. At Syracuse during his past stint, Treinen worked on throwing his breaking ball harder. He previously threw a hard curveball, but wants it to be more like a harder slider now.

“Something shorter and harder out of my hands that way [hitters] don’t see it, harder to recognize,” he said. “It was successful the last few outings down in Syracuse. I had some good swings [off it]. I was pretty happy with it.”

The Cubs swung at 10 of his sliders and missed three times, and three more produced outs. He also used his change-up against left-handers. Treinen was only mildly happy with how either pitch turned out, but happy with his progress so far this season.

Treinen said a caravan of family and friends got to see him pitch in Chicago and witnessed his first victory. But after the game, he packed up his things, shook hands with teammates, spoke with McCatty and left to rejoin Syracuse — until the next time the Nationals need him.