Starting pitcher Brad Lincoln labored in his third start of the season, lasting only 4 1/3 innings, despite throwing a season-high 87 pitches.
Lincoln gave up four runs on nine hits and a walk with three strikeouts, a product of his inability to command his pitches.
Unlike his last start, when he said he felt gassed after allowing five runs on six hits in four innings and 66 pitches against Cincinnati, Lincoln said fatigue wasn't an issue on Tuesday.
"I felt better out there today as far as my body," Lincoln said. "My arm felt good. They asked me before I went out there for the fifth how I felt, and I told them that I was good. So it was just a matter of just the location was off today. Really just didn't have command of any of my pitches."
Manager Clint Hurdle said Lincoln's breaking ball was inconsistent and that the fastball didn't have its regular velocity. Lincoln's fastball usually averages about 93 mph, but was closer to 91 on Tuesday.
Hurdle worried that this could be a result of Lincoln trying to pace himself as he stretches out from reliever back to starter. Hurdle would rather Lincoln simply pitch aggressively for as long as he can.
Lincoln got off to a strong start to 2012 because he threw downhill and was able to keep balls down in the zone, but he has struggled to do so in his last two starts.
If he can't reclaim those attributes in his next outing, which Hurdle said is scheduled for Sunday against Cleveland, then Lincoln could be put back in the bullpen.
"We need him to pitch better, and he knows that," Hurdle said. "We need to get him back on track if we're going to keep him in the rotation."
The majority of the damage against Lincoln came with two outs. The Orioles were 5-for-8 against him in those situations, including a second-inning two-run home run from Mark Reynolds and a flurry of three consecutive singles in the third that was capped by a bloop, run-scoring single from Adam Jones.
"It's definitely frustrating, but it's one of those things where I just need to focus that much more and bear down and put guys away when I need to," Lincoln said.
The only other run Lincoln allowed was to the final batter he faced, when Jones hit a towering solo shot to the seats in left.
On both of the homers, Lincoln missed up in the zone on 2-0 pitches, hanging a curveball to Reynolds and grooving a fastball to Jones.
"You have scouting reports," Hurdle said. "They don't mean to throw them in the hot zone, but hitters have hot zones. When you throw them in there, that's kind of why they call them hot zones. We hit some hot zones tonight."
Lincoln threw 56 of his 87 pitches for strikes, but got himself in trouble by falling behind in counts. He threw 11 of 22 first-pitch strikes, including just 4-of-12 against Baltimore's top four hitters, a big reason why the group had seven hits against him.
"You've got to swing the bats," Jones said. "Tonight, the top of the lineup got after Lincoln and made him pay with a few runs."
Chris Resop and the defense combined to give up four more runs in the sixth. Former Pirate Steve Pearce reached on Clint Barmes' first error in 31 games and moved to third when Resop threw Endy Chavez's bunt single into right field.
Brian Roberts, playing his first game in more than a year, plated a run with a sacrifice fly before J.J. Hardy brought another home with a single.
Chris Davis followed with a two-run homer to right-center on a fastball that caught too much of the plate, pushing Baltimore's advantage to 8-2.
Pittsburgh's offense put forth an effort that would've been enough most nights, but came up short on Tuesday.
Designated hitter Matt Hague got the Pirates on the board first when his single up the middle scored Andrew McCutchen in the first inning. After not homering during the season's first two months, Casey McGehee hit his second in eight days when he smacked a solo shot to right.
Barmes led off the seventh with a single and Alex Presley followed with a double. A groundout from Neil Walker and a sacrifice fly by McCutchen plated them, bringing the score to 8-4.
Walker added a two-run homer in the ninth when he put the barrel of the bat on a hanging slider from Kevin Gregg. The blast was part of a 2-for-5 day for Walker that also included a double off the wall in center when he got the fastball he was looking for from Baltimore starter Wei-Yin Chen.
During his last eight games, Walker is 14-for-35 with three doubles and two homers.
"[I'm] just focusing a little bit more and seeing fastballs, hitting fastballs and reacting," Walker said. "That's usually when I'm going good is getting the barrel out and not thinking, much just reacting. Just being a little bit more aggressive."
Although the ninth-inning blast made the score 8-6, the efforts of Walker and the offense proved to be too little, too late.
"Just put it behind us and come back tomorrow and play our game," Walker said. "We could've easily rolled over tonight when they got up big, but we've got a lot of fight in this locker room. We've got a lot of guys that can play the game, and this is a good team. So we'll be ready to play tomorrow."
With the Reds' victory against the Indians, the Pirates dropped to second place in the NL Central.