Padz did not just show up 2 weeks ago, trust me. There are only a handful of Thunder fans around here, and he is one of the biggest.
Having lived in OKC for the last 4 years, i have noticed that a lot of folks around here did not grow up in OK and moved here for work (myself included). Many of those people still root for their hometown teams (rockets, spurs, etc). But I would agree that prior to the Thunder & Hornets, the Mavs were probably as popular as anyone else.