Before A’s pitcher Dallas Braden kicked off the chic new trend for 2010, perfect games were something of a rarity. Perfect games were baseball’s Halley’s Comet, a sight to be savored with the knowledge that it will be years before you see it again.

Between 1880 and 2009, there were 18 perfect games.

But between this May 9 and June 2, there were darn near three. Halley’s Comet keeps circling back.

Only a blown call by umpire Jim Joyce prevented the first season in baseball history with a trio of perfect games. Joyce ruled incorrectly Wednesday that Detroit Tigers pitcher Armando Galarraga was late covering the bag, giving Jason Donald an infield single with two outs in the ninth.

Nevertheless, the officially recorded masterpieces by Braden (May 9) and the Phillies’ Roy Halladay (May 29) give baseball two perfect games in a season for the first time since 1880.

That’s eighteen-eighty, Jamie Moyer’s rookie season.

In a question akin to asking why the Loch Ness Monster keeps popping up or why the rash of UFO landings, here goes:

What’s the deal with all these perfect games?

“How do I explain it?” Minnesota Twins manager Ron Gardenhire mused. “They’re putting a magical moon dust on the ball this year, and it’s taking all the hits out of the bats.”

He smiled.

“Anything else you need explained?”

Actually, Gardenhire’s magical moon dust is as reasonable as some of the other explanations put forth. Twins pitcher Carl Pavano argued, similarly, that it must have to do with the alignment of the stars and the planets.

Here’s a look at some of the other theories:

It’s A Coincidence, Silly: The most common, and most boring, explanation for nearly having three perfect games in a month is that it’s simply a freakish deviation in the baseball continuum. Statisticians Sean Forman and Andrew Kamholz wrote a piece for the New York Times noting that between 1880 and 1968, perfect games came about once every 11,500 games. Since ’68, they have come about once every 8,200 games.

“That means the frequency of this exceptionally rare event has increased just a bit,” they wrote. “If a couple of umpire calls or ball bounces go another way, the numbers could just as easily be reversed.”

They found a slight change in this year’s offensive output compared to peak years but added that in 2010 teams were still averaging 12 hits plus walks per game and concluded that “this run of perfection on the mound is a random event rather than a result of some underlying change in the game.”

Baseball Prospectus writer Jay Jaffe, responding to an e-mail from the Mercury News, said it’s important to remember that there are roughly twice as many games in the 30-team, 162-game era as there were in the 16-team, 154-game era.

Perfect games happen about 0.005 percent of the time.

“Looking at the results of a single year, there’s really no sensible interpretation for the distribution of no-hitters and perfect games other than randomness,” Jaffe wrote. “The standard deviation for the percentage of no-hitters is 0.056 percent, which means that about two-thirds of the time we should expect to see between 0.3 and 5.7 no-hitters per year.”

The De-Juiced Theory: Former All-Star pitcher Bert Blyleven, whose 287 career victories included a no-hitter in 1977, subscribes to the Coincidence Theory.

But if he had to put his finger on another factor, Blyleven said the crackdown on performance-enhancing substances seems to be having an effect. “Maybe the ball isn’t jumping off the bat like it did during the steroid era,” he said.

Entering play Saturday, the American League was batting .260, the NL .256. Both marks were each league’s lowest since 1992.

“The game for the past few years, maybe longer, was all about the three-run home run,” said Blyleven, now a Twins broadcaster. “Now, we’re getting back to a time when it’s all about small ball and getting that runner in from third, just like it was in the 1960s, ’70s and most of the ’80s.”

Still, as Blyleven acknowledged, the math doesn’t add up. There were more perfect games during the muscled-up 1990s (four) than there were during any other decade. Jaffe, the Baseball Prospectus writer, argued that the offensive potency of an era doesn’t matter as much as people think. “If we check the correlation between scoring levels by decade and perfect game frequency,” he wrote, “we find that the relationship is essentially random.”

The Give-Them-Some-Credit Theory: Braden, not surprisingly, thinks the guy throwing the ball has a little something to do with the recent perfect games. “There are some pretty good pitchers in this game right now,” Braden said.

Braden is in such awe of Halladay, for example, that he didn’t want to bother him with a congratulatory message. “The guy’s thrown more complete games than I’ve got innings in the big leagues,” he said recently.

Pavano, in his 12th season, agreed that the pitchers deserve credit. He said Halladay “has the stuff to do it every time out” but said other pitchers, such as Braden, help themselves by working fast and throwing strikes. “I think you’re seeing a better ball-strike ratio than you’ve seen in some years past,” Pavano said. “That’s what Braden did. He knows that a batter can make contact, just make sure (the batter) doesn’t square it up.”

Then again, pitching talent doesn’t necessarily equate to perfect games. Walter Johnson, Christy Mathewson, Greg Maddux, Roger Clemens, Steve Carlton and Tom Seaver combined for 2,139 career victories — and zero perfectos.

Of the 18 pitchers to throw perfect games before this season, five are in the Hall of Fame and another (Randy Johnson) will be. But there are also four pitchers — Lee Richmond, Charlie Robertson, Don Larsen and Len Barker — who won fewer than 100 career games.

Larsen, for example, was 3-21 for the Baltimore Orioles in 1954, just two years before he twirled the all-time classic in the World Series.

The High-Tech Positioning Theory: In Braden’s masterpiece against the Tampa Bay Rays and Halladay’s gem against the Florida Marlins, most of the batted balls were hit right at defensive players. (Only in Galarraga’s game was there a spectacular defensive play: Austin Jackson’s over-the-shoulder catch in center field.) Those balls being hit right at people are not always a matter of luck. A’s manager Bob Geren noted that there is so “much more information available now about how to pitch guys, how to position guys, than there was 10 years ago.”

Detailed breakdowns and hit charts are available of where a batter is likely to strike the ball. There are also DVDs opponents can study to see how a batter reacts to a particular pitch selection in a particular count. Dizzy Dean never had it so good.

Gardenhire, however, maintains that trying to explain the perfect games is as futile as trying to hit Halladay with a chopstick.

“I go back to something (late Twins owner) Carl Pohlad told me years ago: Baseball is a game of cycles,” Gardenhire said. “That always stuck with me. Right now, we’re just in one of those cycles where (perfect games) are happening.

“That’s the best explanation: cycles. That and magical moon dust.”

Contact Daniel Brown at dbrown@mercurynews.com.