Much of that initial success has come courtesy of excellent pitching. Seattle's starters had been 4-0 with a 1.62 ERA in their first five games, but the A's got five runs off Ramirez in his four-plus innings of work.
The 23-year-old normally relies on excellent command, but he walked three and threw just 49 strikes in 83 pitches while becoming the first Mariners starter this season to allow more than two earned runs.
"I was fighting trying to throw strikes," Ramirez said. "My strength is putting the ball in play, just throwing the ball in the strike zone and making the hitter swing the bat. But today, I don't know. I didn't feel it. I didn't feel like the strike-thrower I am."
Manager Lloyd McClendon said it was all part of the learning curve for his young rotation, which also includes rookies James Paxton and Roenis Elias.
"I think what we have to understand, particularly with young starters, they're so hyped up with that first start, letting everything hang out," McClendon said. "Now he's coming back on regular rest, and it's probably a bit much. He wasn't as sharp. I would suspect he'll be better his next time out."
Ramirez, who held the Angels to two runs in seven innings in his debut, is now 1-1 with a 5.73 ERA.
Veteran right-hander Chris Young replaced Ramirez in the fourth and threw two perfect innings in the first relief appearance of his 10-year career in the Majors. Young, 34, was signed to be Seattle's No. 5 starter two weeks ago, but his initial outing was skipped when Friday's game was postponed due to poor field conditions in Oakland.
Young was moved into a long relief role for now, and he responded with an efficient 22-pitch effort with two strikeouts, though he did allow Ramirez's final run to score on a sacrifice fly to center by Jed Lowrie.
"The results were good, and that's all that matters," Young said. "As the innings build, I can evaluate a little more. But today it was nice to get out there and get my feet wet and keep improving."
Dominic Leone replaced Young and threw a scoreless seventh in his Major League debut, surviving a leadoff double and two-out walk.
"That really kind of calmed me down," Leone said of being greeted by Eric Sogard's two-bagger to right-center. "I know that sounds weird, you give up a double and you'd think, 'Wow,' you get all hyped up. But I think it settled me down, and I realized this is still baseball and I have to execute my pitches, that's all."
The A's made it 6-3 when Yoenis Cespedes led off the eighth with a home run off Yoervis Medina, and new Oakland closer Jim Johnson slammed the door in the ninth for his first save after two rough outings in his first week.
The Mariners took a 3-0 lead after three innings against A's right-hander Sonny Gray, but he settled in and got through six with a 5-3 lead before turning things over to Oakland's outstanding bullpen.
Mariners center fielder Abraham Almonte continued his aggressive high-risk, high-reward play with an RBI single in the second off Gray before getting thrown out trying to go first-to-third on Brad Miller's own run-scoring base hit to right for the third out -- with Robinson Cano standing on deck.
"I tell my guys I want them to unleash their talent, be aggressive," McClendon said. "But you also have to be intelligent. I said it before: He's going to make some mistakes. In that situation, you have to know we have our best hitter coming to the plate. You [should only] go to third standing up. In this game it's unfortunate, but the only way to learn is by making mistakes. And you learn from them."
Cano extended his season-opening hit streak to six games, and his heads-up baserunning led to a run in the third. Cano led off with a double on a lazy looper to center field that Coco Crisp waited back on, only to realize too late that Cano was running hard to second the whole way.
Cano then moved to third on a wild pitch and scored easily on Justin Smoak's base hit up the middle for a 3-0 lead.
But Ramirez gave up a three-run homer to Brandon Moss in the bottom of the third that tied the game as the A's designated hitter drove a 2-1 fastball into the right-field seats. Oakland tacked on two more in the fifth to end the young right-hander's outing.
Smoak has a team-leading eight RBIs in the first six games, and Cano is hitting .391 after Sunday's 1-for-4 outing as the Mariners prepare now for Tuesday night's home opener with the Angels.
"Any time you can come back off the road with a winning record, regardless of how you got there, it's a successful trip," McClendon said. "I told our guys, it was a tough one today, but we had a successful road trip. We'll get home, rest up and be ready to play in front of our fans. I know they're all excited to get there."