Leap Day occurs every four years. So should Will Ferrell sports comedies that range from middling chuckles to embarrassingly long dead spots.

Unfortunately, they’ve become the most depressing annual event this side of somberly remembering a death in the family, and Semi-Pro, Ferrell’s 1970s basketball comedy, is no exception.

As is his par for the course, Ferrell is generous to good supporting players and generates a couple of chuckles. Yet whether targets are tired (sports-movie cliches, white-guy Afros, ’70s fashion) or ambitious (sports’ contractions and mergers in small markets, the ’70s’ wildly awful sports promotions), Ferrell and friends mostly misfire. There’s nothing even as funny here as in the only intermittently amusing Blades of Glory or Talladega Nights: The Ballad of Ricky Bobby.

The new Ferrell goon is Jackie Moon, and Semi-Pro opens with “Love Me Sexy” — the funny, funky one hit that we learn was more blunder than wonder for Jackie. Nevertheless, it earned him the cash to become owner, coach, player and promotions director of the floundering Flint Tropics.

Naturally, Jackie isn’t good at any position. Ford Mavericks roam the streets of this Michigan town carrying more people than Jackie lures to games. As power forward, he’s as much a wannabe as Semi-Pro is of Slap Shot, indecisively tapping balls from the top of the key to the perimeter. And when a grungy hippie fan (Jackie Earle Haley) swishes a $10,000 shot, Jackie can’t pay up.

It seems Jackie is a return to old-school Ferrell — effective, wise and hilarious use of comedy as an entrance point to his characters’ pathetic natures and eventual redemptions. Yet when the Tropics are threatened by the hurricane of an NBA merger, he becomes an inconsistent bore.

Rather than fold while the four most-popular teams transfer to the NBA, Jackie proposes the top four ABA finishers advance. Mired in last place, it’s a long climb, but trading the team’s washing machine for washed-up Ed Monix (Woody Harrelson) provides the spark this team needs.

Semi-Pro’s R-rating does little more than toss cursing into a brand of “random” comedy that’s now become cursory. Yet it’s too timid to show Ferrell vomit on Harrelson in one of many jokes that accelerate with humor before crashing and forcing us to watch a minute of punchline wreckage.

Harrelson revives his retro Kingpin haircut and romantic-loser persona of White Men Can’t Jump (in a boring fling with Maura Tierney), but lacks either role’s charm or comic timing. Instead, with Andre Benjamin as an overly selfish Tropic, he’s forced to carry embarrassingly straightforward sports-film scenes so stiff that they’re almost funnier than any silly shenanigans. And for a film with a predictable game climax, the basketball scenes lack punch or pizzazz.

Just as deflated are Jackie’s “crazy” promotions, which either shamelessly crib from Anchorman: The Legend of Ron Burgundy (Jackie fighting a bear) or quite simply pale next to real-life debacles like Cleveland’s 10-Cent Beer Night or Chicago’s own Disco Demolition Night.

Occasionally, Semi-Pro subs in some inspiration during its clearly improvised ramblings — the reaction to “jive turkey” as a putdown, a brawl timed to start and end with a commercial and any scene with Will Arnett and Andrew Daly as Tropics color men commenting on the idiocy they see. Otherwise, Semi-Pro is the like the movie in the mind of a 10-year-old who’s discovered profanity, pornography and a shoebox full of blank Mad-Libs — funny only to the person coming up with it.