It didn’t have to be this way. Or maybe, it was always going to be this way. Yet, it’s still incredibly strange to watch the translation from stage to screen of a Tony-winning smash hit musical, “Dear Evan Hansen,” go so horribly awry.

Or perhaps, despite the fervent fandom and the awards for best musical, best score, best actor and best actress, this musical about a depressed, isolated teenager who gets caught up in a big, bad lie about a classmate’s suicide was a bit suspect to begin with.

There’s much to unpack, including, of course, the much-ballyhooed casting of star Ben Platt, who originated the title role when the musical premiered six years ago, and reprises the role for the film at age 27.

Platt strains credulity playing a shy, insecure and lonely teenager not so much because he looks too old, but rather that his trying to seem young is so sweatily effortful.

Indeed, the Evan Hansen who appears onscreen in the film directed by Steven Chbosky is one of the most bizarre cinematic portrayals of a teenager, due to all the effort to make Platt, a certifiable hunk, look and seem like a nerdy social outcast with crippling anxiety.

From his curly bangs and wan complexion to his awkward postures and constantly darting eyes, it’s a characterization that may have worked on stage but doesn’t in close up.

Steven Levenson adapts his own award-winning book for the musical to the screen, which is loosely based on an incident that took place at composer Benj Pasek’s high school. The story’s perspective is focused on Evan, an isolated kid with no friends and an overworked single mom (Julianne Moore). He’s highly medicated, and tasked by his therapist with writing cheerful, pep-talk letters to himself.

On the first day of school, another student, the troubled Connor (Colton Ryan), zeroes in on Evan, screaming at him, scrawling his name on the cast of his broken arm and snatching his letter. Noticing a mention of his sister, Zoe (Kaitlin Dever) Connor pockets the print-out and storms off. When he later commits suicide, and the letter is found on his body, his parents, Cynthia and Larry (Amy Adams and Danny Pino) assume it’s a suicide note to his only friend, Evan.

Assumptions and lies tumble out of control, as Evan loves being embraced by this wealthy and warm family, as well as the closeness to his crush, Zoe, while Cynthia loves thinking that her disturbed drug addict son had a friend.

“Dear Evan Hansen” has a serious protagonist problem. Though he may be unliked, and even unlikable, we still need to root for Evan through two hours and 17 minutes of musical melodrama, which means at least one character on screen needs to like him. “Top Gun” doesn’t work without Goose, and Evan’s got no Goose.

While all of this is happening, characters are frequently breaking into song, tearfully belting earnest ballads written by Pasek and Justin Paul (“La La Land,” “The Greatest Showman”) in kitchens and bedrooms and pep rallies.

The leap to the “movie realistic” world on screen removes the veneer of artifice afforded by a theatrical setting, and the film simply cannot sustain that level of cognitive dissonance, combining these songs with Platt’s performance, and the plot, which claims to be about mental health awareness though there’s nary a shred of insight about that issue.

Movie details: PG-13 for thematic material involving suicide, brief strong language and some suggestive references; 2 hours, 17 minutes. Grade: C