Buck went 3-for-4 with two doubles, two runs scored and what turned out to be the decisive RBI on a single in the eighth that made it 8-6 while hitting from the No. 9 spot in the order to lead a 12-hit attack.
And the 33-year-old veteran worked well with Maurer, a talented young prospect who sometimes fights himself on the mound.
"He's so competitive, when he yanks a curveball, he wants to make that pitch again, rather than reacting to the count or hitter," Buck said. "I explained that to him in about the third inning and he kind of rolled with me a lot more after that and was more efficient with his pitches.
"He wasn't climbing back from the two missed pitches, because he had to throw a curve to show himself he could do this. It's not about that anymore. It's about going to what's going to help us get outs and be more efficient. I told him, 'That's why I won't put that finger back down. I know what you want.' And he was like, 'OK.' It was kind of a light coming on for him."
On the heels of a 9-8 victory on Saturday, the Mariners also lit up the scoreboard for a second straight day. With three doubles and a triple, they knocked Astros starter Collin McHugh out with six runs (five earned) in the first four frames. McHugh saw his ERA rise from 0.59 to 2.79 as he suffered his first loss in three starts.
Buck's veteran presence was beneficial there as well, as he played with McHugh last year with the Mets and knew what the right-hander likes to throw.
"It helped a little," Buck said. "My approach was, I knew how he threw last year and the stuff he's been doing that's really made him successful this year. So I kind of went after that. That was my game plan and it worked out."
The victory pulled the Mariners within a game of .500 at 14-15, as they've won seven of their last nine since snapping an eight-game skid. Seattle took two of three from the Astros, who fell to 10-21.
Seattle is 4-1 on a tough cross-country trip that started with a pair of wins in New York and now concludes back on the West Coast with four games in three days in Oakland.
Robinson Cano hit his first triple as a Mariner to highlight a four-run third inning that also included a two-run double by Willie Bloomquist and an RBI single by Corey Hart.
Cano went 2-for-5 with two RBIs, driving in Seattle's first run with an infield grounder in the first and plating Bloomquist with his triple in the third.
Center fielder Michael Saunders and designated hitter Hart each had two hits, a run and an RBI.
Maurer is now 1-0 with a 6.92 ERA in three starts since moving into the rotation after injuries to James Paxton and Blake Beavan. He wobbled again in the fifth as his pitch count climbed, but manager Lloyd McClendon stayed with him after a home run to Jonathan Villar and a walk and single with no outs.
The skipper pulled Maurer in the fourth inning in his previous start in a similar situation, but this time let him go with a 7-4 lead. And the youngster retired the final three batters to put himself in position for his first win.
"It was a battle, but I saw something I liked in the kid today," McClendon said. "I saw some fortitude and guts. He went at it. He didn't have much left, but he fought through that fifth. That's a real tough position to be in, with a short bullpen and a guy that is one of your starters and has an opportunity to win. You want to believe in him, you want to give him an opportunity and he came through."
Maurer said his arm strength still isn't all there after three starts, but he's progressing and appreciated his skipper's support.
"That was a big hurdle to get over there," he said. "It felt good that he left me in there to get out of it."
Tom Wilhelmsen pitched two perfect innings of relief in the sixth and seventh, but Charlie Furbush gave up two hits leading off the eighth and both runners scored when pinch-hitter Marc Krauss greeted Danny Farquhar with a first-pitch single.
Farquhar retired the next three in order to get out of the eighth with an 8-6 lead, then allowed one run in the ninth before holding on for his first save of the season, as closer Fernando Rodney was given the day off due to a recent heavy workload.
Farquhar said he was told just before the game he'd be closing if needed and to be ready to pitch two frames, if necessary, which is exactly how it played out.
"We've been playing some crazy games with these guys," said Farquhar, who pumped his fist after getting Matt Dominquez to strike out on a high fastball for the final out with the [potential] tying run on first. "To get that last one and take the series and finish it on a strikeout, I threw it over his head, got lucky, he swung. Yeah, it was definitely a 'Yes!' factor."