I live in Georgia, and Nathan Deal is nowhere near that popular. A 57 percent approval rating would make him more popular than Chris Christie.
Isn't Insider Advantage a Republican tool poll? Yupp, Nate Silver over at 538 ranked them 2nd worse pollster of the 2010 midterms, only better than Zogby.
http://www.fivethirtyeight.com/search/label/pollster%20ratingsLooking at their final 2010 polls, they overestimated Isakson by 13, but were slightly generous to Barnes (showing him by 6).