"I feel like we have the hitters who can hit, but we are not as aggressive as I would like to see," Nationals manager Davey Johnson said. "Our one and two hitters [Desmond and Stephen Lombardozzi] were aggressive. They swung the bat and got a couple of hits. But we are not centering on the ball. We are not getting a good strike and driving it. The talent is there."
Two of their players -- Ryan Zimmerman and Michael Morse -- are on the disabled list, and it's clear they are missed in the middle of the lineup.
"It unfortunate that those guys are out at the same time," LaRoche said. "It definitely changes the whole lineup. ... It would be great to have them back. We just need to stay afloat."
It was also Bryce Harper's home debut in Washington, and he went 0-for-3. In the second inning, he struck out swinging on a changeup.
"I was throwing quite a few," Cahill said. "I know he's got a quick bat, so I was just kind of hopefully having him speed it up and pulling the string on it a little bit."
Three innings later, it looked like Harper had a base hit up the middle, but shortstop John McDonald was positioned to the left side of the second-base bag, grabbed the ball and threw Harper out at first base.
"I haven't seen the shift since I've been in college," Harper said. "I was trying to make something happen there and get us going."
In his third at-bat in the seventh inning, Harper grounded out to first baseman Paul Goldschmidt.
"I was chasing some pitches I shouldn't have," Harper said. "Everybody is going to throw me differently. They are going to try to throw the off-speed."
Harper nearly threw out McDonald at the plate from left field without a bounce in the seventh inning, but home-plate umpire Jeff Nelson called McDonald safe on a close play. The replay showed that McDonald was tagged on the leg before he touched home plate.
"He's a talented kid, no doubt about it," D-backs catcher Miguel Montero said about Harper. "He's got a great arm. I didn't know that."
Said Harper of the throw, "I thought I had a shot. Reared back and gave it my all. That's what I tried to do. Try to make plays like that."
Right-hander Jordan Zimmermann allowed four runs -- three earned -- in 6 1/3 innings for Washington. Arizona scored its first run in the fifth inning against him, with Goldschmidt scoring on a single by McDonald.
The D-backs made it a 2-0 game the next inning, when Justin Upton scored on a double by Montero.
Arizona added two more runs in the seventh inning. With the bases loaded, Ryan Mattheus hit Aaron Hill with a pitch, scoring Cody Ransom, and McDonald scored on a sacrifice fly by Upton. The runs were charged to Zimmermann.
"The pitchers have been outstanding. Zim is strong," Johnson said. "He got a little tired late. The ball started coming up, but it's going to put a strain on the pitching staff if we don't start scoring runs. He just can't be that fine all the time."
In Zimmermann's five starts, the Nationals have averaged fewer than three runs per game. Asked if he feels he needs to be perfect every time he is on the mound, the righty said, "I really don't think of that when I'm out there. I just think about pitching my game and going as deep in the ballgame as I can. Whatever the outcome may be, it's what it's going to be. I can't really speak for the offense. I just have to go out and pitch the way I can pitch."
The Nationals have lost five straight games and dropped their record to 14-9.
"Something needs to change. It's up to the individual hitter," said LaRoche, the only regular position player on the Nationals who is hitting over .300. "Some guys are chasing. Some guys are being too passive. When you look at that lineup, it's kind of different for about everybody. It's comes down to finding a way to get it done, and we haven't been doing it.
"We have been relying on our pitching. They have been saving us a lot of these games. But sooner or later -- like tonight -- it's going to show up when you have to score some runs."