Jason Cole of Yahoo! Sports has written a story looking back at how Aaron Rodgers came back from his concussion last December. From Yahoo!:
Sitting in his house late last season trying to deal with the effects of his second concussion, Rodgers said that’s when he found the focus that led to a six-game winning streak for the Green Bay Packers. That turned a teetering, injury-marred season for Green Bay into a Super Bowl championship as Rodgers played four brilliant games and two others in which he managed to beat heated rival, the Chicago Bears.
It's a long article with a lot of quotes, and this is just a small part of it. Go read the entire thing.
Taking a brief glance at Aaron Rodgers's game stats doesn't show an obvious improvement over the last six games of the season. But he certainly did seem in a zone (except when playing the Bears, who always cause him problems) and he had two great games against two of the best pass defenses (Giants and Steelers) in high pressure situations.
I do think the concussion gave him a late season break and recharged him before the final stretch of the season, but it seemed like he just picked right back up where he left off.