Though plenty funny, Taika Waititi’s Next Goal Wins is kind of a mess.

Adapted from Mike Brett’s and Steve Jamison’s 2014 documentary by the same name, the fact-based story of disgraced soccer coach and former player Thomas Rongen (Michael Fassbender) taking the last-resort job of leading the notoriously bad American Samoa men’s national team suffers from a leaky script that’s missing significant character motivations and development.

Not only is it unclear why anyone on the team is drawn to play this particular sport, but the writing by Waititi and Iain Morris (The Inbetweeners) also presents a spotty portrait of Thomas beyond his fondness for booze, which doesn’t seem to affect him nor cause anyone on the island nation to raise an eyebrow. Fassbender does what he can with this half-formed character but frequently comes off as miscast and/or the victim of a whole bunch of cut footage.

Seemingly in a rush to get to Next Goal Win’s all but guaranteed happy ending, the filmmakers fail to commit on any front. Inconsistently absurd, it’s the first Waititi film since Boy to merely tap on the humor pedal instead of flooring it, yet his trademark wacky humor bubbles up often enough on the practice field and around the community to sustain viewer interest.

Waititi also doesn’t seem to know what to do with the team’s transgender player, Jaiyah (Kaimana), or various local customs, awkwardly treating both as exotic details that Thomas magically comes to accept despite exhibiting some pretty strong ignorance early on.

But such unconvincing revelations are Next Goal Win’s specialty. From its manipulative 11th hour revelation of the source of Thomas’ woes to the way “the big game” plays out, nearly all of the film’s heartfelt moments feel unearned — a shame since the supercharged underdog story feels tailor-made for Waititi’s skillset.

Grade: C. Rated PG-13. Now playing at AMC River Hills 10, Carolina Cinemark, Grail Moviehouse, and Regal Biltmore Grande.

(Photo: Hilary Bronwyn Gayle/Searchlight Pictures)