The recently released film “Garden State” pokes fun at the convention of serious actors earning credibility by playing the mentally handicapped (see: Sean Penn, “I Am Sam”; Tom Hanks, “Forrest Gump”; Dustin Hoffman, “Rain Man”; Juliette Lewis, “The Other Sister”).

No matter how gimmicky it may be, I was still wowed by the tender, funny work the cast of Is What It Is Productions’ “The Boys Next Door” put into the quartet of mentally challenged roommates who form the heart of Tom Griffin’s play.

There’s Arnold Wiggins (played by Franc Gaxiola) who says he’s “basically a nervous person,” whose pushover demeanor earns the audience’s empathy and whose childish tics — like commandeering floor mats for attention — earn satisfying laughs.

And there’s Norman (Peter Good), an overweight donut chomper whose liberal exclamations of “Oh, boy!” (spoken in that singsong-y “Rain Man” way) and awkward romantic advances with a mentally challenged girl shamelessly tug at our heartstrings.

The four actors and their co-directors, sisters Tricia and Lisa Arnseth, have taken delicate care and attention in respecting and articulating the characters, tastefully avoiding what could have been uncomfortable clichés.

Less attention is paid toward finding a cohesive central story in Griffin’s 1986 play, which is ostensibly about Jack Palmer, a burnout whose wife has left him and for whom supervising the boys (actually men in their late 20s to 50s) in a group apartment home is little more than abject frustration.

Unfortunately, actor Matt Dixon as Palmer can’t quite flesh out his role, so wiltingly un-nuanced in a play surrounded by retarded characters brimming with nuance — and the Arnseths don't seem to have attempted resuscitation.

With Jack’s story line pushed into the background, all the audience is left with in this production is a pastiche of funny, sometimes poignant, scenes with our four retarded antiheroes. “Garden State” is plagued by the same problem of plot cohesion and yet, like that film, “The Boys Next Door” still manages to succeed, no matter how unlikely — or how gimmicky — that may be.