Why Brock Purdy Struggled Against the Seahawks

The difference lies in the secondary.

Everything was set up for Brock Purdy to have another huge game.

He was facing the Seahawks, who barely showed up. He never trailed. His run game was outstanding. He had the threat of play action all game. And his defense was lights out. And yet, he threw a pick-six in the third quarter, struggled big time for most of the second half and finished the game with a pedestrian passer rating of 86.7. And sure, he put away the game with a nice 28-yard touchdown pass in the fourth quarter. But by that point, he was up by 11 points and had let the Seahawks back in the game. He put out his own fire.

What happened? It wasn't even a week ago that Purdy finished a game with a perfect passer rating against the Buccaneers. What did the Seahawks do differently than Tampa Bay?

The difference lies in the secondary.

To stop Purdy, the opposing defense has to shut down his top two receivers -- Brandon Aiyuk and George Kittle. Against Tampa, Kittle had 8 catches for 89 yards, and Aiyuk had 5 catches for 156 yards. Against Seattle, Kittle had 3 catches for 19 yards, and Aiyuk had 2 catches for 50 yards. And that's because the Seahawks have the safeties to cover Kittle and the cornerbacks to cover Aiyuk.

So on Thanksgiving, the 49ers' passing game had to go through Deebo Samuel, who had a good game as a receiver -- 7 catches for 79 yards. But in the second half, he had only 2 catches for 9 yards, because there aren't that many ways to get him the ball and the Seahawks adjusted. Samuel is a poor route runner, so Kyle Shanahan has to scheme him open, and there are only so many ways to do that before the opposing defense catches on and shuts him down, as the Seahawks did in the second half. As a result, Purdy's second-half quarterback rating was just 77.

It will be interesting to see what Purdy does when good defenses follow the Seahawks' defensive game plan.