BBT has landed some pretty odd roles throughout his, ahem, checkered career. There's a lot to choose from, but Lorne Malvo in Fargo the series might be some of his weirdest, so bad it's good acting. I had the distinct impression that he was a) under-rehearsed and b) didn't give a fuck. The series is utterly meh, too much a rote rehash from the original film, so it can at least be said he did inject something different.
Yeah, I quite liked the series, but I know what you mean. It really goes for the "Fargo the Movie" look and feel. BBT was definitely a stand out. The second and third seasons are rather different though. Unusual to have a television show packed with high profile TV and Movie stars across three seasons.