After the affably quirky “Station Agent” and the quietly heartbreaking “The Visitor,” writer-director (and, outside his own movies, actor) Thomas McCarthy takes a mildly disappointing step backward with “Win Win,” a conventional family dramedy that can best be described as cuddly.

Paul Giamatti, doing his quite familiar lovable curmudgeon shtick, plays a struggling small-town lawyer and family man (married to the invaluable Amy Ryan) who spots a way to make a few extra bucks from the state by volunteering guardianship for an aging client (Burt Young) and then dumping him in a retirement home. Shortly and conveniently after this, the old man’s teenage grandson Kyle (newcomer Alex Shaffer), a soft-spoken Emo type with bleach blonde hair, shows up hoping to stay with Gramps, having run away from his irresponsible mom.

Guilt-ridden and seeing no other alternative, Giamatti takes the kid in, and even more conveniently, Kyle turns out to be a state champion wrestler (as Shaffer actually is), which Giamatti coaches as a sideline. Predictably, Kyle gradually ingratiates himself with his new family, and yet more predictably, evil, money-grubbing Mom (Melanie Lynskey, who it’s just nice to see working) shows up at the opportune moment to disrupt everything, awfully reminiscent of the cartoonish family scumbags who show up at Hillary Swank’s bedside in “Million Dollar Baby.” In fact, Margo Martindale, who played one of them, is cast here as Lynskey’s lawyer, as if begging for the comparison.

The film’s only surprise is a lack of one: McCarthy hasn’t got much up his sleeve and seems to have no higher ambition beyond generating a few smiles and nods. The sole signs of his signature quirkiness come from the always amusing Bobby Cannavale as Giamatti’s bumbling pal, who eagerly bullies his way onto the coaching staff and into a rivalry with fellow coach Jeffrey Tambor, in a role that wastes his wondrous gifts so much that his character eventually just evaporates. All of this is well-intentioned and diverting enough; it’s the sort of movie you can take your parents to. It wisely declines to build to the obligatory climactic wrestling match, but then again, it doesn’t really build to much of anything, only to leave us with a completely baffling coda that just screams screenwriting laziness. It’s harmless enough, far more tolerable than the previous Giamatti-as-ueberschlub vehicle, the atrocious “Barney’s Version,” but McCarthy fans (and Giamatti’s) will be left wanting more. Let’s call “Win Win” a tie.