The Mariners also got a three-run blast by Romero in the fourth inning to overcome a 5-2 deficit as they improved to 30-28 heading into Wednesday's finale of the two-game series.
"We're really coming together as a team," said Buck, "Whether it's the bullpen stepping up tonight collectively as a group to throw up zeros and keep us in that ballgame, or whether it's [Endy Chavez] coming up from Triple-A and getting those doubles right off the bat last week that made a difference, or [Brad] Miller, who has been struggling, getting those big hits the other day and a couple more tonight.
"It seems like somebody new every time, which is good. It takes a lot of the pressure off, so everybody doesn't feel like they're the one that has to do it. It'll just naturally happen. When that happens, good things happen, with the ebb and flow of a game and nobody trying to do too much."
Buck hit 15 homers last year for the Mets and has 134 in his 11-year career, but Tuesday's opposite-field pop was his first for Seattle and it capped a 3-for-4 day in which he scored three runs and hiked his batting average from .220 to .267.
Buck's blast came off reliever Alex Wood with two outs, after Dustin Ackley kept the inning alive by beating out an infield single on a grounder to first. The veteran catcher said he owed Ackley for setting up the go-ahead scenario.
"I'm going to thank him for hustling," said Buck. "I was blowing him down the line."
"I think we owe him something," Ackley said in response. "I'm pretty sure that's the way it should go."
After early deficits of 4-0 and 5-2, everything went Seattle's way in this one as Atlanta saw its three-game winning streak snapped and is now 31-26. The Braves had beaten Seattle five straight times dating back to 2008, which was the last time the Mariners played at Turner Field.
Ramirez gave up five runs on eight hits in three innings after being recalled from Triple-A Tacoma earlier in the day to replace the demoted Brandon Maurer. Ramirez wound up with a no-decision and is 1-4 with a 6.82 ERA in seven starts this year.
Ramirez allowed four runs on five hits in the first inning alone as the Braves teed off in a hurry, with catcher Evan Gattis supplying the big blow with a three-run opposite-field home run.
"I was just missing my spots too much," Ramirez said. "The things I wasn't doing in Triple-A, I did here and I paid for it. They took advantage of every mistake I made."
Manager Lloyd McClendon pinch-hit for Ramirez when his turn to bat came in the fourth in the Interleague game and the move paid huge dividends when Romero launched a three-run homer to tie the game at 5 and take Ramirez off the hook.
"I made a living pinch-hitting and I don't know if people realize, to do that is a very hard thing to do," McClendon said. "It just shows the type of talent this young man has, and he's starting to become comfortable in this league."
Romero said he thought he was going to be asked to bunt the runners over with no outs, so his eyes lit up a bit when he saw third-base coach Rich Donnelly give the hit sign. His blast was his third of the year and raised his RBI total to nine. It was Seattle's first pinch-hit home run of the year.
"Obviously it's a great feeling," said the rookie out of Oregon State. "I haven't had too many homers in the big leagues. It's never going to get old."
Relievers Tom Wilhelmsen, Dominic Leone and Danny Farquhar shut out the Braves on two hits with seven strikeouts for five innings after replacing Ramirez, before Fernando Rodney came on to record his 15th save with a perfect ninth that included two more strikeouts.
Wilhelmsen jokingly said he figured he might have a chance to get his first Major League at-bat when the call came to the bullpen so early in the Interleague game.
"That's the first thought in my head," Wilhelmsen said with a laugh. "It's going to happen in Atlanta. I grew up rooting against Atlanta, so I was like, 'I'm going to hit a home run. It's in the stars. I'm going to hit a home run.'"
Instead, he settled for two scoreless innings before McClendon pinch-hit for him as well, working his bench to the point that catcher Mike Zunino was the only remaining position player available at the end. The bullpen also got plenty of action after Ramirez's early exit.
"It was a huge day for us," said Leone, another rookie who recorded four of the strikeouts in two perfect frames. "It all started with Tom. We just fed off his energy coming in and just tried to seal that win."
Robinson Cano went 3-for-5 with a double in his second game back after missing four days with a bruised left hand. Miller and Michael Saunders each had two hits as well, as Seattle totaled 10 hits in five frames against starter Gavin Floyd and 13 for the game.