Washington Nationals pitcher Tanner Roark (57) warms up from the mound in a spring exhibition baseball game against the Houston Astros, Friday, March 7, 2014, in Viera, Fla. (AP Photo/Alex Brandon) (AP Photo/Alex Brandon)

It may have happened on a backfield rather than in a ballpark, against prospects rather than big leaguers, but Tanner Roark submitted a powerful statement Tuesday afternoon in his bid to claim the final spot in the Nationals’ rotation.

Having been washed out of his scheduled start yesterday, Roark pitched in a minor league game in Viera against a busload of Tigers prospects. The start took added urgency after the Nationals moved Ross Detwiler, previously a fifth-starter candidate, to the bullpen. General Manager Mike Rizzo, Manager Matt Williams, pitching coach Steve McCatty and a handful of other Nationals officials gathered behind a chain-link fence to watch Roark pitch.

Roark allowed only two hits, both singles, and struck out seven in 72 pitches and what amounted to about seven innings of work. More impressive – and more important – than those results was how he pitched. He located all of his pitches wherever and whenever he wanted to. Roark touched 94 miles per hour with his fastball, keeping it low in the zone and moving it to both corners. He twirled first-pitch strikes with curve. He sprinkled in enough change-ups. No matter who stood in the box, Roark was awfully sharp.

“You try to get a read off what he does with the hitters,” McCatty said. “The minor league guys are a little bit different sometimes, not used to the breaking balls or whatever. But I thought he spotted the ball extremely well. He threw his offspeed. He was able to drop the curveball over for a strike. I thought it was really good.”

“It wasn’t the 98-mph stuff that everybody’s always raving about,” McCatty added. “It was just the location of pitches and pounding the zone with strikes. I thought he did a really nice job.’

With Detwiler in the bullpen, Roark will compete against Taylor Jordan and veteran Chris Young for the last spot in the Nationals’ rotation. The pressure has not daunted Roark, who thrust himself into the mix with his revelatory call-up season, when he went 7-1 with a 1.51 ERA.

“We talked about it in the winter,” McCatty said. “I’m not sitting here wanting him to create a competition. I want him to go in knowing he threw the ball extremely well last year, and to carry it over however it falls out. He said, ‘I don’t care if I’m start or if I’m in the bullpen. I just want to pitch.’ That’s the way he’s taking it. He just wants to go out and compete.”

This afternoon, Roark mowed through Tigers minor leaguers. The Nationals wanted Roark to throw about 70 pitches, and his dominance rendered the pursuit comical at times. He came out to pitch five times, but he breezed through rapid-fire innings so quickly the Nationals extended the innings and kept their defense on the field for four or five outs.

In his final inning, Roark had thrown at 50 pitches. After a soft liner, a looking strikeout and a grounder to first, he still had about a dozen pitches left. He induced two quick groundouts, both breaking bats. “He can’t get up to 20 pitches!” a Nationals scout remarked. Finally, after two more strikeouts, Roark walked off the mound.

“They had to call out and send in some more bats,” McCatty said. “Because he was blowing some up.”

As a side note, the Nationals’ other minor league game was started by a pretty impressive pitcher, too: Lucas Giolito, the Nationals’ best prospect. He fired his fastball mostly around 95 miles per hour, topping out at 98. His power curve barreled into the home at 82-83 mph.