I feel like every one of these cases can be explained though.
2010: 28-0 vs Chicago.
This was quietly one of the most important Seahawks games ever played, because it taught Pete the value of building a press man coverage scheme. Chicago's DBs pressed and mauled and held Seattle's receivers in a way that would have drawn 15 flags today, but with the emphasis not being there in 2010, they got away with murder and jumped up 28-0 by the time Seattle was able to adjust to it.
A few months later, Pete Carroll drafted Richard Sherman and Byron Maxwell in the late rounds and began copying Chicago's blueprint for press coverage. We all know the results since then.
2012: 14-0 vs Washington.
Washington had two good drives to start the game, and that was it. Seattle adjusted more quickly to the read option in that game than most NFL teams had that season. By halftime, Seattle was barely trailing, 14-13.
The Redskins had won 7 in a row going into that game.
2013: 20-0 vs Atlanta.
10am starts don't actually impact visiting offenses at all, but they do impact defenses. Atlanta connected on some big plays and Seattle's defense got their ass kicked by an old RB who was just about out of the league. The next week, Atlanta played SF at 11am, a full hour later, and jumped out on SF 17-0. 10am starts matter, especially when facing a good offense in their building.
Seattle's offense moved the ball well in the first half, but found ways not to score thanks to a series of ill-timed gaffes by players. When Atlanta ran into their locker room, they couldn't believe they were up 20-0, since yardage wise it was actually a pretty competitive first half.
2015: 9-0 vs Minnesota.
-6 degrees at kickoff. The Vikings got to practice in it all week. Seattle could not. 'Nuff said.
2015: 31-0 vs Carolina.
This was a triple threat scenario. 10 am start vs. an elite offense, horrible field conditions that Seattle couldn't adjust to for almost half a game, and it happened against a 15-1 opponent that got 15 wins by not missing chances like these pretty much ever. Lynch's unfamiliarity with the offense may have contributed to the early pick-six as well.
Carolina seems to rely on momentum more than most teams. So does Seattle. The conditions gave Carolina an opportunity for them to bury Seattle early and they did. And though Wilson is a mentally tough QB, he's as susceptible to bad momentum as anybody.
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The one criticism I have for Pete is that his record has shown that Seattle is not a very good team at planning for strange or unusual game situations. This is the one area that I think Bill Belichick separates himself from Pete. Granted, the Pats don't play a ton of road playoff games, but they always looked prepared when they did.