Berken, who had lost nine of his past 10 decisions, pitched three scoreless innings before landing in trouble in the fourth. Oakland's first run scored on a sacrifice fly, and Landon Powell followed with a two-run home run. After that, Cliff Pennington singled, stole and moved up on an error before scoring on another sac fly.
Mazzaro, a loser in eight of his past nine decisions, took that lead and his shutout into the sixth inning. Aubrey Huff broke up the shutout with a two-run homer, and Luke Scott doubled and scored on an error by center fielder Rajai Davis. The A's went to the bullpen, though, and stranded the potential tying run at third.
"We scored three, had the tying run on third and didn't get the tying run in," said Trembley. "I thought that swung it back in their favor. We were trying to get the momentum back on our side. We went through some good at-bats, but we needed a couple shutdown innings late out of the bullpen and it didn't happen."
For Berken, it represented another loss in a long string of difficult decisions. The right-hander won his big league debut and then lost eight straight times before pulling out a victory over Toronto in his last start. And then he came out Wednesday and stranded a runner at third in the first inning and the bases loaded in the second.
Berken (2-10) snapped in the fourth, an inning that started with a double by Tommy Everidge and a single from Ryan Sweeney. Berken seemed to escape damage on a long fly by Mark Ellis, but then Powell sent a homer deep to right field. From there, Pennington made Oakland's fourth run happen with his feet.
"Overall, I didn't have the best stuff," said Berken. "I was out there mixing pitches early in the game. ... It was obviously a big inning. For whatever reason, that's been something that's hurt me all year. It's just been that one inning. If you look over at a lot of my starts, the bad ones have come over one big pitch or one bad inning. At that point in time, you've got to limit it to one or two runs if you can and try to stay out of a four-, five- or six-run inning."
The Orioles (47-67) had a few chances, most notably a rally spoiled by a diving catch from Davis in the fourth inning. Baltimore didn't break through against the A's (51-63) until the sixth, and that inning was more a near-miss than anything else. Ty Wigginton popped out and Cesar Izturis struck out with the tying run on third.
"I wouldn't say I'm pressing," said Wigginton of his crucial at-bat. "I felt like I had a good pitch to hit. And any time you get a guy in scoring position with one out -- especially a guy on third with less than [two] outs -- that's got to find a way to be automatic. In my opinion, there is no excuse for not driving that guy in."
Baltimore, which held a meeting for position players before the game, had another opportunity dashed by overaggressive baserunning. The Orioles pushed runners to first and second with one out in the seventh, but Nick Markakis was thrown out at second while trying to follow a steal attempt by Brian Roberts.
"I should've known better," said Markakis. "The way Brian steals bags, it's tough to read. That's why he's one of the better basestealers in the game. The way he does it, you can't teach it and it's hard to get a read off it. I should have stayed put and gave Aubrey a chance to get a sac fly or drive in a run there. I took a gamble and came up on the short end."
Oakland tacked on an insurance run on a wild pitch in the eighth inning and scored again in the ninth to account for the final margin. Only one team in the American League has a worse record than Baltimore, which has gone 7-19 since the All-Star break. Twelve of Baltimore's past 18 losses have been by two runs or less.
"It's tough," said Markakis of his team's recent struggles. "This game is not easy, especially when you get in pressure situations and you've got guys in scoring position. For the most part, I think guys are pressing too much with runners in scoring position, even myself lately. We're trying to scrounge up so runs any way we can."