Like On the Waterfront meets the WWF on roller skates, this 2004 show comes from Hollywood playwright Rolin Jones, one of the principal scribes on Showtime's Weeds. What's a jammer, you say? He's like a running back in football, if I understand it—the one a roller-derby team most counts on to score points, which involves getting past or eliminating other skaters.Surprising then that Jack Lovington (Nick Edwards), a good Brooklyn Catholic boy holding down two jobs, who sometimes goes to confession several times a day, is one helluva natural talent on the rink. Over the protestations of his fiancée, Aurora (Jessica Stepka), and his parish priest, Father Kosciusko (Michael Blum), Jack decides to join a three-month tour in an effort to take his sporting career to the next level.Unfortunately, "Gentleman Jack," as he's known on the boards, is in for a lesson in the harsh realities of the world, '50s style, as his 90 days on the road take him from Howdy Doody to daddyhood. His manager and benefactor, Lenny (Ashley Bagwell), tries to keep him from pining for his absent girlfriend by paying one of his teammates, an unbalanced hellcat on skates named Lindy (Christine Nelson), to sleep with him. He's such a newbie that now he's in love with her, even as he sits in a clinic being treated for the cornucopia of STDs he's picked up from their single night of passion.This might all be vastly more entertaining if it were tongue-in-cheek. But director Terri Weagant presents it in almost documentary fashion. Did Jones really intend it all to be deadly earnest, an object lesson in how simple and guileless life was half a century ago? The characters all say what they mean, there's no subtext or dramatic countermelody woven through the story, and even the rat finks are easy to spot from a distance. The Balagan players deliver the dialogue straight, and in often disastrous Brooklynese—Edwards often sounds more like Roger Rabbit than a mook from Flatbush.So what Weagant is left with is the spectacle and the vortex of energy that swirls around roller derby as a sport. Comically enough, all the props and set pieces are on skates, and they make a splendid racket moving on and off Jen Butler's minimalist stage. The skaters themselves simply mime their skating, often with the assistance of cardboard cutouts.A handful of performances are worth watching. Edwards, dialect notwithstanding, is so convincing as a sweet kid that you almost wince for him every time he descends to another level of Hell. Wild-eyed Nelson is as thrilling to watch as a case of nitro bouncing off the back of a pickup. And Blum's parish priest is the picture of benevolent guidance. The world he knew—where everyone speaks English, men don't leave home "to find themselves," and women supposedly don't have sex outside marriage, let alone end their pregnancies—is slipping away.At 90 minutes, The Jammer is a quick dunk into that long-gone world. If you liked Ike, loved Lucy, and burst into tears when you saw pics of Elvis shorn by the Army, well, I've got a show for you.