It's been that kind of week for the Athletics pitchers.
Parker's rough start to the season continued when he gave up six runs in 5 1-3 innings, and Oakland went on to lose to the Baltimore Orioles 10-2 on Thursday night.
"It's kind of embarrassing," said Parker, who struck out five and walked three. "If I go out there and throw a clean inning it's a completely different ballgame. It's something that turns the game the other way. Right now we're letting small things roll and snowball a little bit."
Coming off a 1-5 road trip, the A's didn't get much relief at home.
They managed just six hits, got only two runners past first base after the second inning, and have now dropped eight of 12 since a nine-game winning streak.
The troubles against Baltimore started after the A's scored two unearned runs in the second inning. The Orioles responded with three in the third, one in the fifth and two in the sixth before coasting the rest of the way.
"That's been a problem for us," Oakland manager Bob Melvin said. "It was just an ugly game, a bad game all around."
Nate McLouth reached base four times and scored twice, Nick Markakis drove in two runs, and the Orioles opened their longest road trip of the season by routing the A's.
Chris Davis homered and had two RBIs, Adam Jones added three hits and Jason Hammel pitched six strong innings to help the Orioles win for just the fourth time in their last 20 games at the Coliseum.
Baltimore had a season-high 15 hits, with all nine starters getting at least one. Six players drove in runs.
"It's a good start to a tough road trip," O's manager Buck Showalter said. "Hammel struggled a little but that was what we needed to get through the game and help the bullpen get back on track."
Josh Donaldson doubled in two runs for the Athletics, who have dropped six of seven.
McLouth singled, doubled, walked and reached on a fielder's choice in six at-bats. The Orioles leadoff hitter drove in two runs and is batting .444 (8-for-18) over his past six games.
Parker (0-4) allowed six runs over 5 1-3 innings and is winless in five starts this season. He struck out five and walked three.
"For our guys to battle and get two runs, and then (me) go back and give it up, it's something that needs to change," Parker said.
Baltimore's offense helped overcome an uneven night by the defense. The Orioles turned three double plays but also committed two errors which led to both of Oakland's runs in the first inning.
Shortstop J.J. Hardy bobbled Brandon Moss' grounder. After Josh Reddick walked, Donaldson hit a deep drive that glanced off the glove of retreating center fielder Jones for a two-run double. Jones had initially broke in on the ball before trying to hustle back.
Third baseman Manny Machado's two-out throwing error kept the inning alive but Hammel retired Coco Crisp to end the frame.
Hammel (3-1) was otherwise stellar while giving up three hits and two walks with two strikeouts.
Baltimore's Opening Day starter settled into an efficient groove after the second, retiring nine of 10 at one point. He also worked out of a two-on, one-out jam in the sixth by getting Moss to foul out before Chris Young flew out to center.
Troy Patton pitched two innings and T.J. McFarland worked the ninth to complete the six-hitter.
Baltimore took the lead with a three-run third.
Nolan Reimold doubled and scored on McLouth's RBI single off Parker. After McLouth stole second and scored on Markakis' hit, Jones hit a double down the left field line to drive in McLouth and put the Orioles up 3-2.
McLouth made it 4-2 when he doubled leading off the fifth, was sacrificed to third and scored on a sacrifice fly by Markakis.
Davis hit his eighth homer of year, a solo shot in the sixth, to tie J.P. Arencibia of Toronto for the AL lead. He also singled in a run in the eighth.
McLouth also drove in a run on a fielder's choice. He has reached base safely in 16 of his last 25 plate appearances.
Matt Weiters hit a bases loaded sacrifice fly and Hardy added an RBI single in the seventh for Baltimore.
Notes: A's pitching coach Curt Young was ejected in the third inning for arguing with first base umpire Jim Reynolds. ... Injured Oakland slugger Yoenis Cespedes (hand) went 1-for-4 with two strikeouts and an RBI in his first game of a rehab assignment. Cespedes is eligible to come off the disabled list Sunday. ... The A's reinstated INF Adam Rosales from the 15-day DL and optioned INF Andy Parrino to Triple-A Sacramento (PCL). ... Oakland sends LHP Tommy Milone (3-1) to the hill Friday. Milone had won five straight starts before losing to Tampa Bay last Sunday. ... LHP Wei-In Chen, who opposes Milone, has a 0.71 ERA in two career starts against the A's.