This particular recent summer night had become a celebration of a surprisingly special 2012 season for the A's, with five homers from four players who weren't on the roster a year earlier adding up to a 20-run outburst against the Red Sox.

The flags were waving wildly in the bleachers, they were moving like "Bernie" and the scoreboard at O.co Coliseum lit up like a fireworks display.

A little lost in the hullabaloo was the other line on the scoreboard, where arguably the biggest reason for the A's remarkable road to contending in September was highlighted.

It read "2" for the visitors, and that meant another excellent outing for the Oakland pitching staff, which has been among the Majors' best despite vast turnover and an influx of youth last offseason.

Manager Bob Melvin -- having attempted to explain Brandon Moss' four-hit, four-RBI night and George Kottaras' first career two-homer game -- acknowledged afterward that 20-run games are obviously rare, but two-run games need to continue to be standard operating procedure. After all, two runs by the opponent not being a rarity explains why the A's are at the forefront of the American League Wild Card race, dueling with the rival Angels this week.

"The further you get into the season, pitching is going to rule," Melvin said. "That's been our strength all year. We've had good pitching all year, and I think the numbers would suggest that."

Indeed, they do. The A's are second only to the Rays in the AL with a 3.39 ERA, which would stand as the best ERA for an Oakland team since a 3.18 mark in 1990 -- incidentally, the last year the A's were in the World Series. Over the past 24 games through Monday's 3-1 win in the opener against the Angels, the A's had a 2.68 ERA -- they're 19-5 over that span.

While their offense has picked it up considerably in the second half, it's with pitching that the A's will have to make their way to the postseason. They apparently will have to do it without a veteran leader in Brandon McCarthy, who was struck in the head by a liner last week. But Oakland's staff has proven to be plenty resilient to this point, moving on without suspended Bartolo Colon while not missing a step.

That it is this particular staff doing it is the biggest surprise of all, considering it was almost completely remade this past offseason in a spate of trades by general manager Billy Beane, and that three members of the rotation are rookies.

Remember, the team that had the Big Three a decade or so ago (with Tim Hudson, Mark Mulder and Barry Zito) had actually done quite well to develop another strong rotation. The A's had a young foursome of Trevor Cahill, Gio Gonzalez, Dallas Braden and Brett Anderson that led the staff to the lowest starters' ERA in the Majors in 2010. By '11, both Braden and Anderson had been beset with arm injuries, and by that offseason, the A's revamped that rotation by dealing away Cahill to the D-backs and Gonzalez to the Nationals.

What they got in return was a pair of rookies in Tommy Milone (from the Nats) and Jarrod Parker (the D-backs' top pick in 2007) who have combined for more than 300 innings and account for 22 of their victories, including Parker's quality start of seven innings while allowing one run on three hits Monday night.

A's pitching coach Curt Young has guided the staff since a Spring Training that included a lot of introductions, and he said the formula for Oakland's success has been relatively simple.

"There's a lot of talent, and we've been doing the fundamental things right -- that's really kind of what works," said Young, who returned from a one-year stint with the Red Sox for his eighth season as A's pitching coach, dating back to 2004. "You get guys throwing strikes and making things happen, making their starts, the bullpen throwing solid, you get a nice consistency, and that's how you get on a roll."

The A's have done it in at least one surprisingly veteran fashion. Namely, Oakland's starters have issued the fewest walks in baseball and the fewest homers in the AL. A's starters are on streaks of 39 games without walking three batters, one off the club record, and had 10 games without walking more than one before Parker's pair Monday night, one off the club record set earlier this year.

Not that the staff has been without veterans. Grant Balfour is back in the closer's role and has converted all 10 of his opportunities since Aug. 11, stepping up while rookie Ryan Cook -- also acquired in the Arizona deal, and the A's lone All-Star representative this year -- is thriving more in a setup role over the past month. As a whole, the bullpen ranks second in the AL and third in the Majors with a 2.78 ERA.

And of course the rotation has benefited from the influence of Colon, before his suspension, and McCarthy, who had just gotten into a healthy groove before his harrowing injury.

"Having Bartolo and Mac there right away in the beginning, the veteran presence was there," Milone said. "They've done a really good job of preparing us for a situation like this where they are not here. It's not only just telling us what to do, but just watching them out there on the mound, even in the clubhouse and off the field -- stuff like that.

"They have made it a lot easier for us to kind of see what we need to do for ourselves as a pitching staff and as us on our own. I feel like that has a lot to do with it. And also, it's just the confidence that we have in ourselves and us as a team and a rotation. That goes a long way, no matter how old you are.

"And winning helps, too."

With the likes of A.J. Griffin and Dan Straily, who takes the ball in McCarthy's stead on Tuesday, pitching in with solid starts and Anderson back in action and in strong form, the A's have been winning. And winning.

Much of the contribution has come from a stable of young arms -- 11 rookies have combined to make 235 appearances for the A's this season, a club record.

"We're very apt to let our younger players perform, and perform in prominent roles, so this is no different from anything else we've done all year," Melvin said.