IMO, this was an impressive win by Governor Walker. Backed by an improving employment and fiscal situation in Wisconsin, Walker prevailed. He likely prevailed by at least 9-12 points, which was greater than what any of the polling had suggested.
As is typically the case, economics was likely far more important than other factors in shaping the outcome. The exit polling showed a slim 50%-48% margin in favor of the collective bargaining changes. However, Governor Walker won by a much more comfortable margin. This highlights the roll other factors (very likely economic ones) played. Detailed exit polling data, if it is available, will provide much more insight.