(Alex Brandon /AP)

For the middle portion of this season, Tanner Roark could not even secure a solid place in Class AAA Syracuse’s rotation. Tomorrow night, he’ll join the Nationals’ rotation with the chance to start staking his claim on one of five spots next year.

After an impressive run of middle relief since he debuted Aug. 7, Roark will make his first major league start Saturday night at Marlins Park. Manager Davey Johnson had wanted to give Roark a chance to start since shortly after his promotion, and he believes Roark should be considered for the back of the Nationals’ rotation next spring.

“I certainly think he deserves the opportunity to start up here,” Johnson said. “And he should be in the mix next spring. He’s done a remarkable job pitching in long relief out of the bullpen. He’s been almost letter-perfect. I like his command. I know Willy Ramos thinks a lot of him, too. I think he’s our best bet to help us win the ballgame, but he’s also a guy we look at to be in the mix for next year.”

Roark began the year as a starter at Class AAA Syracuse, then joined the bullpen for 20 relief appearances. Roark moved back to the rotation and had the best stretch of his career, allowing only 12 earned runs over 48 2/3 innings in eight starts.

In a long relief role with the Nationals, Roark has punched up a 1.19 ERA in 22 2/3 innings. He fired 64 pitches Aug. 31 in 3 1/3-inning relief outing. Johnson said Roark will likely be limited to roughly 80 pitches Saturday night. Roark has thrown his fastball in the mid-90s with excellent command, and having experience as a starter, he doesn’t plan to change anything.

“I think I’ll be pretty much the same guy,” Roark said. “I’ll be able to use more of my pitches. You know what guys are looking for, and you know what pitches you can make.”

>>> Ross Detwiler traveled to Miami with the Nationals and will throw off the mound Saturday for the first time since July 4. A bulging disk has sidelined Detwiler.

Detwiler played catch on flat ground this afternoon. The length of his bullpen session tomorrow will depend on how he feels and he’s throwing, Johnson said. Detwiler will need at least three or four bullpen sessions and a simulated game before he pitches in a game, Johnson said. Even then, if Detwiler is able to pitch in a major league game, the Nationals would only use him a reliever.

>>> Syracuse Manager Tony Beasley joined the Nationals as a coach for the remainder of the season.