"It's fun to watch, fun to be a part of," winning pitcher Chris Tillman said.
The defeat sealed the Phillies' first winless road trip of at least eight games since an 0-9 run in August 1883, their inaugural season. Philadelphia hosts the Orioles on Wednesday after going 0-8 in Cincinnati, Pittsburgh and Baltimore.
"Worst road trip I've ever been on as far as just the way we lost games," said right fielder Jeff Francoeur, who pitched the last two innings. "We were in a bunch of games and just lost them at the end, or one hit here or one pitch there."
Not this one.
The eight home runs were the most by the Orioles since their move from St. Louis in 1954. They hit seven in a game three times previously, the last on Sept. 26, 2012, against Toronto.
"We squared up a lot of mistakes they made," Baltimore manager Buck Showalter said. "It just kind of snowballed."
Ryan Flaherty set the record with a solo shot in the eighth inning off Francoeur, who retired all three batters in the seventh after Baltimore scored in each of the first six innings.
In the eighth, though, he walked three, hit a batter and allowed two runs.
"I kind of got to experience everything that a pitcher probably experiences over a year in two innings," Francoeur said.
Machado set the tone by hitting starter Jerome Williams' second pitch into the seats in left field, sparking a six-run first inning that doomed the Phillies to their 12th consecutive road defeat.
Making his debut with the Orioles after being added to the 40-man roster earlier in the day, Parmelee set a career high with four hits and enjoyed his second career multihomer game. He scored three runs and had two RBIs.
"That's a pretty good way to start, right?" Parmelee said. "But you know, the team played phenomenal tonight."
Tillman (5-7) allowed three runs and four hits in six innings to win his third straight start.
Williams (3-7) left with a hamstring injury after getting only two outs. He was replaced by Dustin McGowan, who yielded five home runs in 3 1-3 innings: second-inning solo shots by Machado, Jimmy Paredes and Parmelee; a three-run drive by David Lough in the third; and a leadoff shot by Chris Davis in the fourth.
"I know what it looked like. So once he pointed at me, you just walk off the mound," De Fratus said.
Maikel Franco homered for the Phillies, who were swept in a third straight series for the first time since 1989. Philadelphia owns the worst record in the majors (22-44) and worst road record (7-28).
Williams left the game after being flattened in a pileup at the plate when the two runs scored on a single wild pitch. The right-hander has surrendered 10 first-inning runs in his last two starts.
Phillies: Franco ranks second on the team with seven homers, and he's only been playing in the majors since May 15.
Orioles: Davis' HR was his sixth to hit Eutaw Street beyond the wall in right field, most in the history of Camden Yards.
Phillies: RHP Chad Billingsley (shoulder) allowed one run in three innings for Triple-A Lehigh Valley on Tuesday in his first rehab appearance.
Orioles: Showalter rested CF Adam Jones, who had an MRI on his right shoulder that showed no structural damage. ... RHP Kevin Gausman (shoulder) gave up one run in two innings during a rehab start Tuesday with Class A Frederick. . RHP Miguel Gonzalez (groin) will throw a bullpen session in Philadelphia on Thursday. If it goes well, he could pitch in a rehab game Saturday or Sunday, Showalter said.
Phillies: Veteran RHP Kevin Correia makes his second start for the Phillies on Wednesday night. He was signed as a free agent on June 8.
Orioles: RHP Ubaldo Jimenez (4-3, 3.19 ERA) starts for Baltimore. He's 0-2 with an 11.25 ERA lifetime against Philadelphia.