Nationals’ left-hander Gio Gonzalez pitched five innings Wednesday, walking seven but earning the win. (Greg Fiume/Getty Images)

As pitchers’ duels go, the one the Washington Nationals won, 2-1, over the Arizona Diamondbacks on Wednesday night qualified as both unorthodox and unexpected.

Nationals starter Gio Gonzalez walked seven in five innings, thoroughly outpitched by his counterpart, but left the game tied. Their would-be fifth starter, Jacob Turner, threw four scoreless innings in relief — as many scoreless innings as the Nationals bullpen has thrown in a single game all season. And in a matchup of the two most potent offenses in the National League, Ryan Zimmerman’s sixth-inning RBI double was the difference.

Asked for his takeaways from the evening, Gonzalez shook his head and said simply, “a win.” He was not credited with a victory after five innings of one-run ball, but his team improved to 18-9, which put the Nationals one win clear of the Diamondbacks for most in the National League.

The whole crazy thing began with Gonzalez, around whom craziness often eddies, and who has spent much of the past three seasons trying to avoid succumbing to its pull. Gonzalez entered Wednesday evening with a 1.62 ERA he built during an uncharacteristic April in which he worked quickly and effectively through five strong starts.

An informal poll of those familiar with Gonzalez’s style revealed a consensus key to his early-season success: the ability to throw his curveball for strikes. When he does that, Gonzalez gets quick outs, stays ahead of hitters and pitches deep into games. When he doesn’t, he battles, because hitters can sit on either his fastball or change-up, knowing the curveball probably will not hurt them.

Matt Wieters has pushed Gonzalez to throw the curveball more often. The lefty entered Wednesday’s start throwing a higher percentage of curveballs (21 percent) than he has since 2013, 12th-highest percentage among qualified big league starters. Gonzalez’s experience in the third inning Wednesday, when he trailed 1-0 after a Chris Owings homer, represented the importance of the pitch.

Dangerous Paul Goldschmidt led off, and Gonzalez used a curveball to get strike two — the difference between a pitcher’s count and a hitter’s count. Two pitches later, he struck him out. Gonzalez then landed a curveball for strike one to Arizona cleanup man Jake Lamb, who grounded out a pitch later.

But Gonzalez missed with a 0-1 curveball a batter later; he let Yasmany Tomas back into a count and eventually walked him. When he landed his curve to Brandon Drury twice a batter later, Drury struck out to end the inning. Ephemeral fastball command caused Gonzalez trouble Wednesday. The extent of his curveball command determined whether he got out of it.

Ultimately, Gonzalez did not have enough command of either pitch to last long Wednesday night. While one or the other sustained him through the first four innings, Gonzalez lost control of both in the fifth inning and walked the bases loaded before using the curveball to strike out Drury again. After 105 pitches, his final line included seven walks, eight strikeouts and three hits.

“Gio walked a lot, struck out a lot. Got out of trouble a couple times,” said Baker, who pointed to the strikeout of Drury as a turning point. “. . . It gave us a chance to win.”

His Diamondbacks counterpart, 2010 Nationals draft pick Robbie Ray, has added a curveball to what used to be a fastball-heavy arsenal — another example of the importance of a third pitch to starting success. After pitching to a 4.90 ERA in 32 starts last season, Ray entered Wednesday with a 3.56 ERA and the highest strikeout rate of his career.

Mixing his inside fastball to right-handers with plenty of curveballs and sliders, Ray struck out 10 Nationals by the sixth. But after Bryce Harper singled in that inning, Zimmerman doubled him home, extending his multi-hit streak to six games — and forcing Ray to leave trailing. Zimmerman was named the National League player of the month for April on Wednesday. He has not cooled.

Turner relieved Gonzalez, a somewhat unexpected twist given that a person with intimate knowledge of the Nationals’ thinking said this week that Turner would assume Joe Ross’s spot in the rotation — pending the outcome of this week’s games.

But the Nationals are short a man in their bullpen right now because A.J. Cole is serving a suspension. Baker revealed after the game that Shawn Kelley was sick and unavailable, too.

After Blake Treinen threw two innings Tuesday, that left Joe Blanton and Matt Albers as the only other righties in the bullpen. So when Turner threw a strong sixth inning, then a strong seventh, Baker decided to let him hit for himself in the bottom of the seventh. He kept pitching.

“I don’t think I’ve ever thrown four out of the bullpen, so I wouldn’t say you come in expecting that,” Turner said. “. . . Once I batted for myself, I felt like I should finish the game.”

Turner’s four scoreless innings are a sign of the times for Nationals relievers, of whom others were available, though Baker avoided even the healthy ones in the kind of one-run game he should be using them to lock down. Cole will probably have to start this weekend because Gonzalez and the Nationals bullpen needed Turner on Wednesday. Right now, this struggling Nationals bullpen, shorthanded and sick, will take what it can get — strange though it may be.