Tanner Roark had a sensational July, but August hasn't treated him so kindly.
Roark went seven innings in each of his five starts and surrendered more than one run only once in July. After putting up a 2.06 ERA for the month, he's sitting on a 4.26 mark entering his fourth start of August against the D-backs on Wednesday night.
"Just need to get back into that groove again," Roark said. "But all in all, feel good, feel healthy, feel confident."
Washington has been in a real groove, bringing a season-high eight-game winning streak into the third game of the series.
Roark has been inconsistent this month, bookending one seven-inning, one-run outing with two non-quality starts in which he gave up a combined eight runs. The Nationals haven't suffered for his rough patch, though, as they lead the National League East by six games.
Roark says that stretches like this happen and results will come again without any major changes.
"Just got to let it happen. Keep doing what you're doing," he said. "Keep your routine. No need to change anything. Don't fix nothing that's not broken. Just go out there and pitch like I know I can."
Trevor Cahill, his opponent on the mound for the D-backs on Wednesday, has had to make major changes this season, and they seem to have paid off.
Cahill spent about six weeks in the Minor Leagues working on his delivery after struggling for the first half of the season.
Since returning, however, he has put up a much-improved 3.53 ERA in six starts. He has picked up victories in his last two starts and hasn't given up more than two earned runs in a start in since July 29.
Cahill's current 4.68 ERA is the lowest it has been all year, and his strikeout numbers are higher in his last three outings (14) than they were in his first three since returning from Triple-A Reno (9).
D-backs: Veteran Ziegler struggling as season goes on
Reliever Brad Ziegler has been one of the most consistent pitchers out of the D-backs' bullpen this season, but in the last several weeks, he has hit a rough patch.
Ziegler has pitched in seven games this month and, in seven innings pitched, has surrendered nine runs (seven earned) -- a 10.50 ERA.
In his last two games, he has given up three runs and been charged with two blown saves.
"This has been a tough trip for him," D-backs manager Kirk Gibson said. "We've been in seven games here, six of them are one-run games, and he's had trouble in three of them, I think.
"He's been through it before. He'll do some work out there and we'll try and find a little ... he's just not finishing his pitches, it looks like, not as much sink on them."
Nationals: McLouth out for season
Outfielder Nate McLouth will miss the remainder of the season with a torn labrum in his right shoulder, the Nationals announced Tuesday.
McLouth will have surgery on the shoulder Thursday.
Manager Matt Williams said he believes McLouth's already-injured shoulder got worse when he dove for a ball in right field in a 7-6 loss to the Marlins on July 28.
"It had been something he has been dealing with all year. The symptoms got bad after that game in Miami," Williams said. "He dove for that ball, and it hasn't gotten any better since."
McLouth is in the first season of a two-year deal worth $10 million, but he was struggling even before he suffered the labrum injury.
In 79 games, he was hitting only .173 with .517 on-base-plus-slugging percentage.
• The Nationals' pitching staff snapped D-backs outfielder Ender Inciarte's team-rookie-record 18-game hitting streak on Tuesday.
Adam Lichtenstein is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.