"Our offense seems to be sputtering. We just can't get anything going. That's our problem," Johnson said. "We are not hitting balls early in the count. ... We have a lot better hitters than we are showing."
The Nationals had a chance to tie the score in the eighth against Pirates right-hander Mark Melancon, but couldn't take advantage.
With one out, pinch-hitter Chad Tracy reached on an error by Pedro Alvarez. After Denard Span struck out, Ian Desmond singled to right field, putting runners on first and third. Bryce Harper came to the plate and struck out to end the threat.
What can Johnson do to jump-start the offense? There isn't much he can do. He can't put right fielder Jayson Werth back in the lineup because he is dealing with a hamstring injury and will not play this weekend. Johnson already benched second baseman Danny Espinosa for two games and inserted Steve Lombardozzi in the lineup.
"We are kind of hitting rock bottom. We just need to man up," Johnson said. "Let's start doing the things we are capable of doing. The ones that get me are the [called strikeouts].
"There not a whole lot of changes I can make. We see a couple of left-handers [the next two days]. Jayson Werth, I can't go there. We pretty much have the right guys. We have to start doing a better job. It's as simple as that."
As for Detwiler, he pitched five-plus innings and allowed three runs on six hits. All three runs came on homers. In the first inning with two outs, Andrew McCutchen swung a 2-1 pitch and hit a monster home run that went well over the left-field wall to give Pittsburgh a 1-0 lead. McCutchen went 3-for-4 and is 41-for-90 (.456) with 11 home runs and 22 RBIs against Washington during his career.
"He is not going to hit a home run every time, but it seems like against us, he does," Detwiler said. "You have to focus on keeping the ball down. Don't let him lift the ball, though."
The Nationals tied the game in the fourth against right-hander A.J. Burnett. Adam LaRoche scored from second on a single by Espinosa, but Tyler Moore was thrown out trying to go from first to third.
"Tyler Moore hesitated coming around [second] and shouldn't have been caught there and Danny should have been on second," Johnson said. "Those things happen. You are never as bad as you look when you lose and you are never as good as you look when you win. It's as simple as that."
Pirates second baseman Jordy Mercer, who was called up from Triple-A Indianapolis on Friday afternoon because of a hand injury to Neil Walker, hit a two-run homer off Detwiler in the fifth to give Pittsburgh a two-run lead.
"I've seen him sharper," Johnson said about Detwiler. "He had trouble getting the ball down. The balls he got hurt on were fastballs up and he hasn't been doing that all year. To me, he had a little command problem. He threw a lot of pitches in a short time. He kept the ball up."
Detwiler knew what he did wrong when he faced McCutchen and Mercer.
"It was kind of weird. It was the same exact pitch," Detwiler said. "I was trying to throw a fastball away. I cut it a little bit. It goes right over the middle of the plate. They are paid to hit them."
But Burnett was the story. He dominated, allowing one run in seven innings and striking out nine. The fourth inning was the only time the Nationals had a serious chance to score against Burnett.
"We were very efficient tonight, mixed in some changeups," Burnett said. "Fastball in early, later away, and mixed in the change in to lefties, that kept them off everything."