As in: The opponents are making big plays. I've sliced and diced the longest plays against Seattle this season. A couple things jumped out as interesting.
Seattle has allowed 10 plays of at least 46 yards. Six of those plays were on the first play of a drive, a disproportionately high number. Sometimes you hear coaches talk about how their teams perform in "sudden-change" situations. Generally they are talking about the plays immediately following turnovers or other bad things. Seattle's defense is allowing big plays to start drives even when there hasn't been a sudden-changen situation.
Opponents have 14 running plays of at least 20 yards. Seven of these were in the first halves of games, before the defense could have "worn down" from being on the field too long. On the flip side, Seattle has allowed eight runs of 17-19 yards, and seven of these were second-half plays. As for those 14 plays of 20-plus yards, my notes show that Seattle probably would have had its base defense on the field for most of these plays. Note, too, that one of these long runs came on a fake punt Thursday night.