"The little things are supposed to make all the difference.

Not for the Seahawks' defense. At least not this season. Size has been everything when it comes to measuring Seattle's improvement.

"One of the most significant things that changed is big plays," coach Pete Carroll said.

A year ago, the Seahawks allowed 76 plays of 20 yards or more, tied for second most in the NFL according to The Associated Press. This season, Seattle has given up just 45 such plays, tied for second fewest.

That explains why the Seahawks have one of the most improved defenses in the league. But it will face a stiff test Sunday in Arizona.

"They've had a lot of explosive plays," defensive coordinator Gus Bradley said of the Cardinals.

Arizona had seven plays gain 20 yards or more in its last game alone, and it has five plays of 40 yards or more in the past four weeks.

Those are the kind of plays that Seattle has been so much better at stopping this season, though it hasn't been perfect.

No one has forgotten Michael Crabtree's 41-yard catch to set up what turned out to be the 49ers' game-winning field goal last Sunday, or the 50-yard touchdown pass the Seahawks gave up to Washington's Rex Grossman in the fourth quarter of the Nov. 27 loss."