Johnson hasn't been able to find enough work for Duke this season and the skipper believes a start will get him going. As a long reliever, Duke has allowed 14 runs in 15 innings.
"Stammen has been very good. I don't want to change him out of the role that he is in," Johnson said. "With Duke, he has been basically a starter. I haven't able to give him the kind of work to keep him sharp. This will help him get back to where he needs to be. It kills two birds with one stone."
This will be Duke's first Major League start since 2011 when he was with the D-Backs. Duke has spent most of his time with the Nationals as a reliever. He is replacing left-hander Ross Detwiler in the rotation because Detwiler injured his lower back against the Dodgers on Wednesday. Detwiler had a third MRI on Saturday and, it turned out, he has a right oblique strain. It's not known if he will go on the 15-day disabled list.
Duke said he is appreciative that Johnson is giving him a chance to start. Pitching coach Steve McCatty informed him of the assignment Saturday afternoon, and the left-hander immediately had a bullpen session. In four games, Duke is 1-0 with a 1.08 ERA at AT&T Park.
"I'm sorry about what happened to Ross. I hope it's nothing very serious. I hope he can come back quickly," Duke said "At the same time, I have to get out there and give us a chance to win the game and re-prove to the organization and to the guys in this clubhouse that I can pitch and get people out."
If Detwiler is out for more than one start, the Nationals will call up a pitcher up from the Minor Leagues. There is a chance it could be a reliever, while they add Duke to the rotation.
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.