Season one episodes certainly seem to agree with your assessment. Pierce started out as just a clueless old white guy. For whatever reason, be it Chase himself or the writers, the character evolved into the asshat he is today.
This isn't always bad. Troy has also evolved away from originally conceived. Many other shows have this happen as well when certain actors begin to find their character's voice or when writers start writing to an actor's strength. Its worked for Jim Parsons on TBBT, and he's even parlayed that into some Emmy wins.