The Seattle Seahawks' defense entered Sunday's game against the 49ers on pace to shatter the NFL record for most yards allowed in a season.
They had been particularly putrid against the pass, allowing a league-worst 368.7 yards through the air per game -- a reflection of their inability to both cover and get after the quarterback, with only nine sacks through six games.
So when the Seahawks announced that they would be without their All-Pro safety Jamal Adams, starting defensive end Benson Mayowa, starting cornerback Shaquill Griffin and starting nickel back Ugochukwu Amadi for Sunday's game -- all due to injury -- many assumed the 49ers would be able to have their way with a depleted version of a swiss-cheese defense.
Clearly, that's not what happened. The 49ers lost 37-27 to their archrival, struggling against the Seahawks' defense throughout.
How does an immensely struggling unit produce easily its best performance of the season while shorthanded against a Kyle Shanahan-led offense? Yes, the 49ers' injuries played a role and the Seahawks surely were amped up for the critical matchup, but the answer lies more in a stylistic change on Seattle's part.
They blitzed the 49ers. A lot.
"We were definitely aggressive. Blitzed a lot more,'' Seahawks linebacker Bobby Wagner said after totaling two sacks in the victory. "It was important for us to get the quarterback off his spot and not let him sit back there and pick us apart."
Seattle's blitzes were very effective. According to ESPN Stats & Info, the Seahawks generated pressure on 17 of Jimmy Garoppolo and Nick Mullens' combined 45 dropbacks in the game, a 37.8 pressure rate that marked Seattle's best in over two years.
Garoppolo was limited to just 84 passing yards, completing 11 of 16 attempts for no touchdowns and one interception before heading to the 49ers' locker room at the end of the third quarter with an aggravation of his high ankle sprain. Mullens was very productive in his quarter of action, completing 18 of 25 passes for 238 yards, two touchdowns and no interceptions, but he took advantage of a prevent defense that was far more QB friendly.
The 49ers' offensive line struggled mightily throughout the contest, frequently overwhelmed by the additional pressure provided by the Seahawks' blitzing. Following the loss, left tackle Trent Williams explained they were caught off guard by Seattle's plan.
"Without [Adams] playing, you know, he's a huge part of their pressure plan, so without him playing, I didn't think they would heat us up as much," Williams told reporters. "But with the lack of pass rushers, I think that was the only way they felt they can get pressure on the QB. It's no excuse, we've got to be better. The blitzes they brought, we should be able to pick them up."
Shoulda, coulda, woulda -- but didn't, and it cost them. The Seahawks' defense might not be as bad as the stats would have you believe, but by failing to adequately prepare, the 49ers made them look better than they are.