"You like to see runs tacked on to give you a little security, if there is such a thing in the American League," Showalter continued. "You could see early on that runs were not going to be at a premium."
Pie's three-run drive over the center field wall off Justin Masterson (4-11) with two outs in the fifth gave Baltimore a 7-6 lead. It came after Arrieta fell behind 6-4 by allowing five runs in the bottom of the fourth after the Orioles had taken a 4-1 lead with four runs in the top half.
"That's disappointing," Masterson said. "You have the lead and you want to keep it. You feel like you let down everyone else. He (Pie) struck it well. We tried to make him put a ball in play, and he (really) put a ball in play."
Corey Patterson hit a solo homer in the sixth, then Matt Wieters had a two-run shot and Luke Scott another three-run drive during the Orioles' six-run eighth.
The Orioles still have the worst record in the majors at 39-74 and worst on the road (15-40). Cleveland has lost eight of its last 10 at home.
"We could have a few more wins with fewer walks and fewer errors," Indians manager Manny Acta said. "We need to face it and we need to get better."
Scott had four RBIs and the 6-thru-9 batters in Baltimore's order totaled eight hits, seven runs and nine RBIs.
The Orioles were 7 for 10 with runners in scoring position and are 29 for 70 (.414) under Showalter.
Asdrubal Cabrera's run-scoring single gave Cleveland a 1-0 lead in the third.
Both teams sent nine men to bat in the fourth. The Orioles' four-run half included an error, a wild pitch, two walks, three hits and a spectacular play by Cabrera at shortstop.
Scott had an RBI double and Adam Jones put Baltimore ahead 2-1 with a run-scoring groundout. With a runner on third, Pie lined a shot off Masterson's left foot. Cabrera, moving to his left, stopped in his tracks, dived to his right and caught the ball barehanded, then threw out the speedy Pie from a sitting position.
"I was mad," Pie said. "I couldn't believe it."
Wieters and Cesar Izturis added RBI singles to make it 4-1.
Shin-Soo Choo's two-run double capped Cleveland's five-run bottom half. Cabrera was thrown out trying to score from first on the bases-loaded drive into the right field corner.
"It was just kind of glad to be out of the inning," Arrieta said. "I just lost command of offspeed pitches in that inning."
Trevor Crowe doubled home a run, stole third, and scored on a groundout by Luis Valbuena. Michael Brantley's two-out RBI single tied it at 4. Brantley had a two-run homer in the ninth.
Baltimore's first four batters combined to hit for the cycle in the eighth off Frank Herrmann. Pie doubled and scored on Wieters homer. Patterson tripled and scored on a single by Izturis to make it 11-6.
Masterson gave up four earned runs over five innings, dropping to 5-17 in 32 starts since being acquired from Boston in July 2009.
NOTES: Cleveland acquired C Luke Carlin from Pittsburgh for a player to be named and sent him to Triple-A Columbus. Carlin has a .252 average in 46 career games with San Diego (2008) and Arizona (2009). He hit .239 for the Pirates' Triple-A team at Indianapolis this year. ... The Indians signed RHPs Cole Cook and Nate Striz, their fifth and 22nd draft picks, respectively. Cleveland's top four picks are unsigned with the deadline Monday at midnight. ... Orioles 3B Josh Bell, in a 3-for-22 slump, didn't start. He was a defensive replacement in the ninth. ... The Orioles improved to 19-46 at Progressive Field since the ballpark opened in 1994 -- with Arrieta only the eighth Baltimore starter to earn a win.