"It was good to see some old friends and be able to talk to those guys," said Millwood, "but it's no fun stinkin'."
The Mariners lost their fourth straight and fell to 1-5 on their road trip, which now swings to Anaheim for three final games after Thursday's off-day.
After an 8-2 homestand, the road has been rough, but Wednesday was the first game the Mariners simply didn't play well.
"We're working through some things with a couple of new guys, getting the opportunity to see what they can or can't do," manager Eric Wedge said. "We've got to be a complete team. We've talked about that time and time again. We've been a good defensive team, but tonight we weren't. Ultimately, we've got to do it in every area of our club to win.
"We've had a tough four days in a row. We have an off-day. We need to regroup and get back on track in Anaheim."
Seattle managed just two runs and five hits in six innings off first-time Orioles starter Steve Johnson, who was promoted from Triple-A after scheduled starter Tommy Hunter had to warm up in the bullpen late in Tuesday's 14-inning victory over the Mariners.
Johnson, 24, had a shutout going until Kyle Seager roped an opposite-field two-run blast in the sixth. It was Seager's 13th home run, tying him with the since-demoted Justin Smoak for the team lead.
Johnson, the son of former Orioles pitcher and current broadcaster Dave Johnson, wound up with nine strikeouts and a good impression in his starting debut.
"It was a battle tonight," said Seager, who had half of Seattle's hits in a 3-for-4 night. "His fastball was pretty sneaky. He hit his spots pretty well. His ball gets on you quicker than you think. I don't know if it came out of his hand funny, but it definitely got on you pretty quick."
The Mariners helped the youngster out a bit in the second when they loaded the bases with one out, but Munenori Kawasaki bunted right back to Johnson and the pitcher threw home for the force, then got Dustin Ackley to pop out to end the threat.
"I don't want that," Wedge said. "I told him that. I don't want him to bunt with the bases loaded there. I don't even know where that came from. I told him, don't do that again."
On the flip side, Millwood didn't get much help from anywhere as the Mariners weren't sharp defensively. The veteran needed 37 pitches to labor through the first on a muggy 85-degree night as the Orioles took a 2-0 lead and never looked back en route to their fifth straight win.
Catcher Matt Wieters drove home both first-inning runs with a double that glanced off the outstretched glove of right fielder Eric Thames as he tried to run it down in the gap.
That trend continued when Nick Markakis tripled on a ball that Thames chased around in the right-field corner before getting it and J.J. Hardy followed with a hard grounder under Seager's glove at third that was ruled an RBI single.
"We didn't help him out at all early," said Wedge. "Of those first four runs, maybe one of them would have happened. We didn't make any plays. We didn't make any errors, but we didn't make any plays. At the big-league level, we've got to make those plays."
After home runs by Mark Reynolds and Markakis made it 7-0 in the fourth, Millwood's night was over.
"To get out of it with just two runs in the first was alright, I had an easy second inning and then it just kind of went south from there," said Millwood. "It's not like it was smoking hot or anything. I just didn't pitch well."
Hard-throwing rookie Carter Capps made his second Major League appearance and went two scoreless innings with two hits and his first two career strikeouts, hitting 97-100 mph with his fastball throughout his 39-pitch outing.
The Orioles pushed across two more runs against reliever Josh Kinney in the seventh. Wieters finished with five RBIs and two doubles and Adam Jones was 3-for-4 with a pair of doubles as well.