The last time the Giants and A's met, you hardly could have guessed you were looking at two future playoff teams.

The Giants had spent almost the entire season trailing the hated Dodgers by anywhere from three to seven games in the National League West standings and fell back to three games out when they lost 4-2 to the A's on June 24. Only two years removed from its delirious championship run, San Francisco had just a single player in the lineup, catcher Buster Posey, who had started in the clinching World Series victory over Texas in 2010.

The Giants were in the hunt that June afternoon, but they didn't seem fully loaded.

The A's were in much worse shape.

Although their typically young team had shown some spark in the early months of 2012, they appeared destined for another year of mediocrity. The victory over San Francisco put Oakland a distant 10 games behind the two-time defending American League-champion Rangers. Many sports fans were still trying to learn the names of the A's everyday players.

And yet here they are today, a pair of division champions, set to unveil something we have seen all too rarely -- playoff baseball on both sides of San Francisco Bay. The A's play this afternoon at the Detroit Tigers, while the Giants this evening host the Cincinnati Reds.

This is the first time since 2003, and only the sixth time since the A's continued their westward migration from Kansas City in 1968, that both Bay Area franchises are playing postseason ball in the same year.

The accomplishment has created a frenzy of baseball throughout the Bay Area, backed by the chants of fans, the drone of play-by-play on TV and radio and the ring of cash registers.

"There is a fever pitch," said John Salazar, owner/chef of Hey Misstir Bar & Grill on Mission Circle in Santa Rosa. "During (Wednesday's) A's game, to have people pouring champagne in my bar, making a mess because they're ecstatic, that's fantastic. There's a fever pitch for the A's and the Giants."

Both teams showed remarkable perseverance to get here. The Giants lost their best hitter, Melky Cabrera, who was suspended when tests revealed elevated levels of testosterone, on Aug. 15. One week later, the A's lost their most experienced starting pitcher, Bartolo Colon, for the same reason.

The Giants have played the entire season without bearded closer Brian Wilson and second baseman Freddy Sanchez, both injured. The A's have played without Dallas Braden, who threw a perfect game in 2010. San Francisco ace Tim Lincecum has spent much of 2012 looking like a minor-league call-up. Oakland ace Brandon McCarthy was hit in the head with a line drive on Sept. 5 and hasn't played since doctors cut into his skull to relieve pressure on his brain.

After tribulations like those, the Reds and Tigers can't seem all that intimidating.

Despite the turnover during the past two years, the Giants remain a confident team. Pitcher Matt Cain has been superb, and Lincecum's inconsistency has been partially mitigated by the surprising turnaround of Barry Zito -- the only player on either Bay Area roster who was here the last time we had dual playoff runs in 2003. Zito pitched for Oakland then.

Even Cabrera's shameful departure didn't knock the Giants off stride, thanks largely to Posey, who returned from a devastating leg injury to hit. 336, win the National League batting title, and make a run at the league's MVP award. San Francisco sealed the division title with deft trade acquisitions that included dynamic outfielder Hunter Pence and scrappy second baseman Marco Scutaro.

The A's ascendancy has been even more remarkable. Without a true star on the roster -- Oakland's only All-Star player was middle reliever Ryan Cook -- the team has instead relied on a 26-year-old rookie outfielder (Cuban export Yoenis Cespedes, soon to turn 27), a shaggy Petaluma native who provided clubhouse leadership (Jonny Gomes) and a shifting core of semi-anonymous power hitters who helped the A's to a major-league best 14 walk-off wins in 2012.

"You know what it is? It's a fairy tale," said Marty Lurie, who handles Giants pre-game and post-game shows for KNBR radio on weekends and previously performed similar duties on A's broadcasts for 12 seasons. "It's almost like the prince has kissed Snow White again, and the flowers are blooming again after having nothing but thorns there for so long. Oakland is alive again."

The A's pitching staff was young in April and got younger as the season progressed, with Colon's suspension and injuries to McCarthy and Brett Anderson. By season's end, Oakland had a five-man starting rotation composed entirely of rookies.

And yet the A's kept winning, sweeping the Rangers in the final three games of the season to happily exchange a wild-card berth for the AL West championship. In the process, they became just the fifth team in Major League Baseball history to overcome a 13-game deficit to win a division title or pennant.

"They used to say rooting for the Yankees was like rooting for U.S. Steel," Lurie said. "That's not Bay Area baseball. We're not U.S. Steel, we're the other guys. And that's what makes our teams so interesting. They sort of come out of nowhere and surprise you."

The ultimate surprise, of course, would be another Bay Bridge Series, as we had in 1989 when the A's swept the Giants in four games (punctuated by a magnitude 6.9 earthquake). An encore feels like a crazy long shot at this point, which means you have every reason to expect it.

You can reach Staff Writer Phil Barber at 521-5263 or phil.barber@presssdemocrat.com.