Packers had the best (or second best, not positive) protection on the year. Because of the short quick hitter type of routes they ran, the weather really didn't matter in terms of protection. Kearney is a speed rusher, which means he goes around guys. This necessarily takes longer than a guy like Reggie White, who took a more direct route. Quick slants and crossing patterns negate a lot of the effectiveness of a rusher like Kearney (who, holy shit, looked amazing in their wild card game).
Seattle just had no answer in the secondary, and as such really didn't have a chance. Plus, without the turnovers Seattle's offensive was impotent, even when the weather was decent.