BALTIMORE -- For Travis Blackley and the A's, Sunday just wasn't their day.
Blackley was slightly off all afternoon and the A's offense struggled against Wei-Yin Chen, ending an otherwise satisfying road trip on a low note as the Orioles avoided a sweep with a 6-1 win at Camden Yards.
Now 18-4 this month after taking two of three in both Toronto and Baltimore, the A's will need at least one more day to secure the win that would give the team its best July in franchise history since moving to Oakland.
"The way we've been playing, it looks like we've got a chance to win every game," A's manager Bob Melvin said. "But boy, any time during the season you can go on the road and take four out of six from two very good teams, we'll take it."
Blackley would like to take Sunday back, struggling to repeat his motion en route to one of his worst starts of the year.
Blackley set a season high with five runs allowed on six hits in only five innings.
Pitching in hot and humid conditions that he said were a factor and "battling" back stiffness that has plagued him in recent weeks, Blackley struggled to keep his mechanics in order long enough to get on a roll.
"Just couldn't seem to find a groove, had no rhythm," Blackley said. "It was just inconsistency with my motion. Sometimes I'd stay through the pitch really well, and other times I'd fall off toward third."
Blackley did set a season high with four walks and a season low with one strikeout in the loss.
The biggest blow was a three-run shot from Matt Wieters to cap a four-run third inning. The blast was only the third homer Blackley has allowed this season.
"It was kind of a rough one," Blackley said. "Didn't take advantage of the counts when I was ahead, and fell behind more than I'd like. I had four walks today, that's not like me."
"This was just kind of an off day for him," Melvin said. "Looked like he was struggling with his command a little bit, fighting himself some, mechanically."
Blackley appeared to be shaken after he awkwardly tried to field a bunt single from O's second baseman Omar Quintanilla to lead off the third. Quintanilla pushed the ball into the grass between the mound and first base, and Blackley slipped on his fielding attempt and was unable to make a throw, ultimately suffering what Melvin called a "whiplash type of effect."
Melvin and team trainer Nick Paparesta went out to check on Blackley and -- after a few warmup pitches -- ultimately left him in the game. After a Nick Markakis flyout, Blackley walked J.J. Hardy and surrendered an RBI double to Adam Jones, putting two on for Wieters' homer.
"I don't want to make excuses for that," Blackley said. "It was just a [bad] day for me. Can't do awesome every time out.
"It's not the first time I've dived for a ball. It's kind of one of those things, man. I didn't really have an answer for them."
The O's extended their lead to 5-0 in the fifth. Hardy led off with a single and Jones walked. Blackley looked like he might limit the damage when Wieters hit a grounder to third, as Brandon Inge threw to second for one out and Jemile Weeks fired to first. But first baseman Chris Carter made his second catching error of the game, letting the ball bounce off of his glove and allowing Hardy to score.
Blackley left after just 93 pitches and five innings, his shortest start since June 10.
"I think we're getting used to some pretty good outings out of him, and it just wasn't his best today," Melvin said.
The A's were probably also getting used to a lot of offense, too, entering Sunday with the most runs and highest slugging percentage in the American League since the All-Star break.
But, like Blackley, the bats were just a little off on Sunday, unable to get anything going against Chen.
The rookie left-hander allowed just one unearned run on three hits in 5 2/3 innings with 12 strikeouts -- the most by a Taiwanese-born player in Major League history and the highest total by an Oriole since July 2007.
"He was just throwing his fastball by us and wasn't afraid to use it," Melvin said. "[He] was throwing it to both sides of the plate and threw just enough breaking balls to keep us off-balance. Pitched a great game."
Melvin said Chen used the fastball "more than we expected," part of the reason he was able to keep the A's hitters from getting a read on his changeup or curveball.
"Everything was working today," Chen said through an interpreter. "My fastball got really good life today, and I located it well."
Chen did the majority of his damage with that heater, using it to record 10 of his 12 strikeouts -- the highest total in Orioles history for a player throwing fewer than six innings.
"He had a little giddyup on his fastball," Weeks said. "Late action. It was causing guys, including myself, to just miss it."
"Once it got halfway through, it was like it picked up speed," first baseman Chris Carter said. "It was pretty deceptive, and he had good stuff today."
Not until the sixth inning did Oakland get on the board, when Yoenis Cespedes singled in a run after Weeks walked and Jonny Gomes reached on an error by Quintanilla.
So reliant on the power game in their second-half surge, the A's notched just two extra-base hits.
The result was the A's scoring only a single run for the first time since July 17 -- a reminder of how strong the team has been this month and during the 4-2 road trip that ended on Sunday.
"We went out there and won series, back to back," Weeks said. "There's nothing more you an ask for on the road."
Greg Luca is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.