Seventy mile-an-hour pitches. Sliders, curveballs, knucklers. O for 25 slumps.

Although it sounds like baseball, it's actually a different American pastime. You might have heard of it - WiffleBall, the new sport craze that's sweeping the nation.

Over the past few years, WiffleBall leagues have blossomed, both in Massachusetts and around the country. There are at least six organized WiffleBall leagues in our state alone, all of which belong to the New England Wiffle Ball Association. Seth Rosen founded Worcester's Wiffle Ball league, called MASSWIFF, three years ago, as a senior project while at Worcester Academy.

"I've been playing Wiffl Ball my whole life," Rosen said. "One day I went to a tournament and fell in love it the game. Anyone can play, yet it's so competitive."

Together with the help of the Worcester Jewish Community Center, Rosen put together a league of 16 teams in its first year. At the beginning, there wasn't much talent, but as word of the league spreads, more and more athletes have been flocking to the field.

"Now it's a real, legitimate WiffleBall league," Rosen said. "The sport is getting pretty big. Leagues are popping up every place."

While WiffleBall bears some similarities to baseball, there are some striking differences - including the signature yellow bat and the number of players, which usually ranges from three to five.

Eighteen-year-old James Nugent says WiffleBall combines the two best parts of baseball - hitting and pitching - and leaves out most of the rest. For example, there's no base running. Singles, doubles and triples are marked by lines on the grass, and homeruns are awarded to all balls hit over the fence. Hitting is challenging, as each batter gets four balls and only two strikes. If the ball hits the black padding behind the hitter, it's a strike. And there's no Money Ball-foul-pitches-off approach, as two fouls produce an out.

Matt Foley, 25, of Worcester knows first hand just how tough it is to get a hit in the league. In his first week playing with second-place Breen's Pub he went 0-25.

"I'm just hoping to get a hit this week," he said, laughing.

Rosen plays for Moneyball, along with his father and girlfriend. Although named after Billy Beane's patient baseball philosophy, Rosen admits that his team doesn't really abide by that rule.

"We swing at everything - although [money ball] is what we aspire to," he said.

'The whole experience'

Eighteen teams currently make up the MASSWIFF league. Ten teams - mostly high school and college players under 30 - play on Sunday. Eight more - usually the over-30 crowd - compete on Tuesday evenings. They combine and play each other during the postseason.

Rosen said that part of the reason why the league is so fun is that many of the players know each other. Adam Fins, 23, of Worcester, agrees. In his third year playing for the league, Fins went to school with many of the current WiffleBall players. As a result, a competitive spirit and camaraderie has developed.

"We joke around a lot and it's something to do on a Sunday afternoon," Fins said.

Rosen believes that another reason why so many players charge the field every week is because WiffleBall allows them to recapture the aura of competitive sports.

"They're still going out and playing hard and icing their shoulders," Rosen said. "It kind of makes you feel like you're playing a real sport again. We have guys talking strategy and scouting other teams. They love it."

Indeed, WiffleBall provides players with the unique opportunity to combine all the major aspects of professional baseball - scouting, the general manager and player - into one. Rosen recalled one player who posts write-ups and stats every week after games. And, earlier in the year, when one of the better teams dismantled, there was a rush to nab the players.

"It felt like there was a free agent market," Rosen said, laughing. "It adds to the whole experience. There's a lot of strategy involved."

What a Blast

With the playoffs scheduled to begin this weekend, it's crunch time. And in case bragging rights aren't enough, there is a thousand dollars in prize money on the line for the top two teams - $700 for first place, $300 for second.

"That's a good little gift in the summer," said Legends of the Hidden Temple player Jon Brennan, grinning. "The playoffs will be a blast."

Brennan, 16, is a converted WiffleBall player after throwing out his arm pitching for Doherty High. One of the more dominating pitchers in the league, Brennan has an assortment of pitches he uses to baffle hitters, including a fastball, curveball, and his favorite - the knuckleball.

Fellow Legends teammate Brendan Sargent, 17, has Brennan to thank for not only learning about the league, but also how to pitch. Sargent used to play WiffleBall as a kid and was ecstatic to learn there was a real league. This is his second season and so far he's enjoyed every second of it.

"Honestly, on Monday I start counting down the days till WiffleBall again," Sargent said. "We take it seriously, but not too seriously."

One of the advantages of WiffleBall is that anyone can play it - both seasoned athletes and those who have never participated in organized sports. Sargent said he's always loved baseball but was never more than average as a player.

"I like that I'm good at Wiffle Ball," he said. "My favorite part of the game is hearing the ball hit the back of the [strike zone] plate - knowing it's a strike. I love to throw strikes and make people look silly."

The Dirt Dogs are currently cruising in first place. The team owes a large part of their success to Nugent's pitching. Although he's never been officially clocked, Nugent estimates he throws anywhere between 60 and 70 m.p.h. The Dirt Dogs' one loss came against the Breens in the ninth inning. According to MASSWIFF's rules, the bases are automatically loaded and a Breens player got the winning hit.

Nugent also pitched for Doherty High, but admits he enjoys playing WiffleBall much more than baseball.

"This is way better," he said. "It's much more relaxed and a lot more fun. ... I'm good at it - that [also] makes it fun."

For his part, Rosen appreciates that a project he began in high school has taken off and proven to be so exciting to so many players.

"WiffleBall is like an art," Rosen said. "You can train yourself to throw a wiffle ball and play in the league."