IT DOESN'T take much exaggeration to skewer the nation's merger-mad, profit-maximizing, service-minimizing health care system as a farce. The San Francisco Mime Troupe sums up "managed care" in one line of one of Bruce Barthol's songs - "The less we do, the more we make" - in "Damaged Care," the latest of its free summer shows in the parks.

Longtime troupe playwright Joan Holden, co-author Karim Scarlata and director Dan Chumley have come up with many telling images to satirize for-profit medicine. The point is driven home in everything from Peggy Snider and Lily Chumley's backdrops - a giant dollar bill with Rx-prescription symbols for dollar signs; a grim, barracks-style ICU ward - to the 1-800-NOT-SICK hot line set up to replace a closed emergency room.

In one sharp vignette, a nurse is stalled on hold as she tries to get critically urgent medication cleared through the hospital's new voicemail system. In a deft bit of slow-motion physical comedy, an orderly with a patient on a gurney plows through an emergency room full of waiting, seriously injured patients (a stabbing victim is dragged out of the way; a man with bus-flattened hand is bowled over).

But the comedy and the message felt underdeveloped at the Mime Troupe's traditional Fourth of July season opening, Saturday afternoon in Dolores Park. The weather was glorious. The sea of sun-drenched attendees roared its approval of guitarist Liberty Ellman's Hendrix-fuzz-style "Star Spangled Banner" and the Sisters of Perpetual Indulgence's comical blessing of the performance.

The crowd laughed at the punch lines and hissed the villains. But "Damaged Care" only sporadically achieved the political incisiveness or comic complexity of the troupe's best work. Too often, it felt uncharacteristically inert.

Holden and Scarlata's script is unusually bereft of the complicating subplots that could amplify their theme, while lacking a plot central enough to keep us engaged. At its core, "Care" is the story of a public hospital, Bologna General, that's been taken over by the rapacious for-profit Capacare and to be downsized and streamlined into a money-making business.

The action centers on four characters, each expertly portrayed by a Mime Troupe stalwart but none with a fully developed story. There's Nurse Basil (a vibrant Velina Brown) and Resident Hemostat (an appealing Keiko Shimosato), the harried remnant of the staff trying to provide care under increasingly impossible conditions.

There's Arlecchino (a delightfully adept Michael Gene Sullivan) - a wannabe wrestler with no insurance, seeking help for a scary lump ( "It's really hard. It's really stinky. And it speaks French" ) - who falls in love with Nurse Basil. And there's the evil Capacare CEO Doctor Capitano (the devilishly funny Ed Holmes), the kind of health care provider who thinks the shame in closing the last emergency room in the city is the fiscal irresponsibility of being the last.

There are other characters as well, including Brighella (an appropriately slinky Victor Toman), a rapacious venture capitalist, the slow-witted orderly Zanni (a capable Amos Glick) and a gravel-voiced female TV reporter (a gruff Toman) more intent on sensational stories than basic health care issues - not to mention various patients and hospital personnel portrayed by the same cast.

As many of those names indicate, "Care" is also a tip of the hat to the commedia dell'arte format of the Mime Troupe's original outdoor shows in the '60s. But - except for the characteristic half-masks, a few touches in Huy Tran's clever costumes and some deft physical comedy by Sullivan - the show makes little use of commedia. Director Chumley and the actors haven't developed the sharply defined stock characters of the genre or exploited its rich legacy of physical shtick (or lazzi).

Nor does "Care" have Chumley's characteristic split-second comic timing, except in occasional bits. On opening day, the show's momentum bogged down in dead moments and slack transitions. Part of the problem seemed to lie in Barthol's songs, with operetta-ish music - by Barthol and band members Ellman, Eric Crystal and Derrek Phillips - awkwardly set on the usually strong voices of Brown and Sullivan.

But it's the skeletal script that remains the biggest problem. Nurse Basil vacillates between quitting and allowing herself to be exploited out of concern for her patients, without her story growing to a real crisis. Capitano's profit-squeezing machinations are under-developed. Arlecchino's story isn't integrated into the main theme.

Scattered throughout the script are clever one-liners playing off the kinds of medical stories that capture headlines ( "Take six Viagras and call me in the morning" ), as well as issues more central to what's wrong with a bottom-line approach to health care: The systematic denial of care by redefining illnesses; the assault on medical workers' unions; the understaffing of nurses; the attempts to shift care to lower-level, lesser-paid staff; the closings of emergency rooms.

There's some terrific stuff here, and even a less-than-standard Mime Troupe show is a very pleasant afternoon in the park - whenever, during the course of the summer, the company comes to a park near you. Given the troupe's history, Holden, Scarlata and Chumley will probably whip the show into better shape before the season's half over. As of Saturday, however, "Care" needed more care.