Patton Oswalt did not receive an Oscar nomination for portraying Matt Freehauf in Young Adult.
Young Adult is a film I thoroughly disliked, and no it's not because the film's central character is unlikable. There are plenty of films I love with technically unlikable leads. The film seems to have a distinct disdain for all of its characters, even the ones presented as happy in some way are presented in a detached fashion as caricatures, though that may have been unintentional. The film's most fervent desire seems to be to make one as uncomfortable as possible while watching it. The majority of the actors are stuck in one note roles, and do not overcome that problem. Charlize Theron tries her best though I would say struggles to find balance with the writing behind the character who too often becomes just a full blown cartoon due to the script. The only other actor with a part that even comes slightly close to breaking out of the square is of course Patton Oswalt.
Patton Oswalt is probably best known for his standup comedy, and just generally being an enjoyable comedic presence in whatever he appears in whether that is a film, tv show, or just in an interview. Now part of the role here plays into that with his portrayal of almost a sitcom "best friend" to Theron's character. The set up isn't exactly that, but Mavis ends up making Oswalt's Matt her confident since she tells him what's she's exactly up to in her homecoming as well as due to his certain supply of alcohol he has at his disposal. Oswalt is often there to offer a few one liners and sardonic remarks at Mavis's expense or at the expense of her idea. Oswalt to his credit does this quite well, and importantly never overplays this element. He allows the humor to come very naturally throughout his performance. He never makes it feel like a zinger exactly, making it feel rather like what Matt would actually say in any given situation.
Mavis and Matt's connection though technically goes a bit deeper than merely their mutual appreciation for a yeast based beverage. The connection stemming from their inability to forget about high school. For Mavis this is seen through her disillusion in regards to her own popularity to the point that she firmly believes that her old flame Buddy (Patrick Wilson) will immediately drop his family to get back with her. Matt's inability to forget is caused by something a bit more concrete in that he was permanently injured due to a vicious attack by bullies in high school. Oswalt is very effective in the two moments where he specifically describes the attack as he reveals the pain in Matt, without breaking down, but as he speaks of the attack Oswalt portrays the very real scars left on Matt. Oswalt never forgets this essential element to his character, underlining it throughout his performance.
In even his lighter moments Oswalt still brings a shade of the bitterness fitting to a man broken due to others' senseless hate. Now with this Oswalt offers two things the film very much needs, a likable presence in the film, and a three dimensional character who never devolves into a cartoon. Oswalt's Matt lives past the frame as you understand his past, even while you enjoy some of his jokes in the present. Now in terms of Matt's relationship with Mavis, Oswalt makes it convincing in terms of his depiction of the sort of the desperate attachment to the past. Where the two end up doesn't exactly work, but to Oswalt's credit he does his absolute best to make the scene in question feel natural on his end. Oswalt doesn't save the scene nor can he save the movie. He improves the film best he can though, acting as the clear standout with his nuanced yet amusing performance.