THEATER REVIEWS / ‘BLEACHER BUMS’ : Team Spirit : The cast puts forth its best ensemble effort in the comedy that depicts America’s favorite summer pastime.

In the entire history of theater, it would be difficult to think of a play that’s more purely American than “Bleacher Bums.” And it would be difficult to think of a more appropriate summer treat. Why, there might even be a lesson or two about sportsmanship and camaraderie among all those laughs.

The show is running at the Conejo Players Theater in Thousand Oaks. Its director, Francine Markow, appeared for several months in the show’s nine-year Los Angeles run.

Set in Chicago’s Wrigley Field, the play follows several die-hard Cubs fans as they kibitz and place bets with one another during the course of a game with the St. Louis Cardinals. To appreciate it fully, one would have to be at least vaguely aware of the rules of America’s Pastime, and cognizant of the Chicago fans’ love affair with their perpetually losing Cubs.

One, too, would have to accept that there is no intermission in “Bleacher Bums,” only a seventh-inning stretch, in which the audience is urged to sing “Take Me Out to the Ball Game” along with the cast. How do you explain that to a Frenchman, a Swede or a Croat?

Even the writing of “Bleacher Bums” comes out of a distinctively American concept: improvisational theater. The script is a joint effort, credited to nine members of Chicago’s Organic Theatre Company, after a concept by then-member Joe Mantegna. (Another well-known member of the group, Dennis Franz, went on to co-star in “Hill Street Blues.”)

Markow’s production is a smoothly running machine. Her cast is an ensemble in the most complimentary sense of the word: There are no stars here.

There is a star turn, however. Sure, the character of Richie is an overly stereotyped nerd. But Scott Barrett takes the part and runs with it, earning several of the evening’s biggest laughs.

Other Bleacher Bums include Melody King (Sheri DeMieri), who’s at least as interested in her suntan as the game; Zig (Stephen Carver), who seems to have the strongest urge to bet on anything; Greg (David Mitchell Karen), a blind fan who listens to the play-by-play on his transistor radio; the Cheerleader (Paul Eierdam), an especially boisterous supporter of the team; Marvin (David McMoyler), who has given up on the Cubs, placing his bets against them; and Decker (J. Curtis Swanson), the most “normal” person of the lot, who forms a sort of center for the group.

A little girl, played by Mindy Mittleman, appears briefly, as does a security guard, played by Jim Leedom. Michael Markow’s set is wonderfully evocative, and it’s Jeff Canitz who puts the lights on in Wrigley Field.

* WHERE AND WHEN

“Bleacher Bums” continues through July 25 at the Conejo Players Theater, 351 S. Moorpark Road in Thousand Oaks. General-admission tickets are $8 for Thursday night performances; $10 for Friday and Saturdays. All shows are at 8:30 p.m. For reservations or further information, call 495-3715.