Even though I never saw it, I've heard a lot of characters got flanderized around season 3
For instance, during s3, Brad became less cool and clever, and turned into an incompetent buffoon who did little more than annoy Jenny. While at the same time, Sheldon got more self-confident, less awkward, and less annoying and began to win Jenny's affections. This was, presumably, the writers' way of showing fans that JennyxSheldon and not JennyxBrad would be the canon ship.
This felt like an insult to Brad fans, so perhaps it's for the best the show got canned, right as it was veering into a stupid direction (as many animated shows tend to do around season 3 or 4).