Despite giving up a two-run homer to Adam Jones in the first inning and two more runs in the fourth on opposite-field hits by David Lough and Ryan Flaherty, Richards (11-3) arguably pitched well to win. Instead, the right-hander absorbed his second successive defeat following a seven-game run that lasted nearly seven weeks.
"I don't think his stuff is much different," Angels manager Mike Scioscia said. "At times, you're going miss some spots and guys are going to hit it. Sometimes you're going to miss some spots and guys are going to foul it off.
"In tonight's game, outside the one pitch to Adam Jones, the two lefties, Lough and Flaherty, put together some good at-bats with guys in scoring position where they went the other way on him. He pitched a good game."
But not as good as rookie Kevin Gausman, who allowed three hits over seven innings in his first career appearance against Los Angeles.
Gausman (5-3) retired the first 14 batters he faced and ended up giving up three runs and three walks.
"He threw his pitches well," Angels leadoff hitter Kole Calhoun said. "He obviously has electric stuff. He's got some good off-speed pitches to complement the good fastball. He threw the ball well, he kept the ball down and they made some great plays behind him too."
Darren O'Day struck out two in a perfect eighth and Zach Britton gave up a single in the ninth before earning his 21st save.
The victory lifted the AL East-leading Orioles to 14 games over .500 (60-46) for the first time July 22, 2013.
"We've been able to stay where we are because of the pitching," manager Buck Showalter said.
Jones put the Orioles up 2-0 with a two-run homer, his second in two nights. It was his 21st of the season and 11th in the first inning.
In the Baltimore fourth, Lough picked up his first RBI since June 7 with a double and scored on a single by Flaherty.
Gausman got some early help from his defense. Right fielder Nick Markakis made a sprawling catch in the third and third baseman Manny Machado snared a grounder down the line and staggered deep into foul territory before throwing out Albert Pujols in the fourth.
The Angels' first hit was a two-run single by Chris Iannetta in the fifth inning after Gausman walked the bases loaded. Calhoun followed with an RBI double.
NOT SO FAST
C.J. Cron thought he had just taken ball four leading off the third inning. He flipped the bat toward the Los Angeles dugout and began jogging in the direction of first base. But it was only ball three. So, after umpire Kerwin Danley waved him back to the plate, Cron grounded out on a 3-2 pitch.
Angels: Left-hander C.J. Wilson (right ankle sprain) threw in the Camden Yards bullpen and remains on course for a possible return from the 15-day DL this weekend.
Orioles: First baseman Chris Davis missed a second straight game with a stomach virus. ... Right-hander Ubaldo Jimenez (right ankle sprain) will likely make his final rehabilitative start Sunday or Monday for Triple-A Norfolk. After his rehab start for Class A Aberdeen on Tuesday, he paid for a postgame spread of steak and lobster.
Angels: Left-hander Tyler Skaggs (5-5, 4.49 ERA) will make his first career start against the Orioles on Thursday night. Skaggs has not walked more than one batter in each of five starts since coming off the disabled list with a right hamstring strain.
Orioles: Bud Norris seeks to continue his mastery of the Angels. In three career starts against LA, the right-hander is 3-0 with a 0.46 ERA.