Since Tyrann went down (and Bethel became the outside CB) and Rashad Johnson returned (putting Swearinger on the bench) - the secondary slowly degraded. Call it the Cary Williams effect to put in Seahawks context, but Peterson was trying too hard to make plays against Carolina and started getting over-aggressive in his pursuits and in trying to take that punt return deep before securing it.
Sucks, but you have experienced something similar in the beginning of the year. We probably have the weakest front 7 of the NFC West, so make adjustments to the comparisons there obviously.