The Seahawks received a reminder that a very talented and supremely motivated team is still capable of beating them. Here are two critical plays in the loss:

Frank Gore’s 51-yard run: In their off-tackle run schemes, the 49ers usually employ an “O” block, which is the backside guard pulling and lead-blocking on a linebacker. On this play, San Francisco used a “G” block, which is the frontside guard pulling and performing a kick-out block — in this case on Bruce Irvin, aligned outside on the line of scrimmage. When Red Bryant scraped inside, left tackle Joe Staley had an easy block on him — a block which also took out Brandon Mebane, aligned one man inside.

The problem for Seattle was that Kam Chancellor, who had outside responsibilities in run support, had followed tight end Vance McDonald inside when McDonald went in motion. Chancellor adequately recovered, but the “G” scheme hits a little quicker than the “O” scheme because Gore doesn’t have to wait for a backside blocker. So, when Bobby Wagner widened with the fullback’s lead block, weakside linebacker Malcolm Smith was not in a fill position from the inside because guard Alex Boone had quickly sealed him off. Lastly, Earl Thomas took an angle unbefitting an All-Pro, and Gore was free.

Colin Kaepernick third-down run: Ahead 17-16, if Seattle won this play, San Francisco would kick a short field goal and Seattle would have more than three minutes to answer. Of Seattle’s four best tacklers on the field, two — Wagner and Smith — were aligned outside the hash marks away from the direction of Kaepernick’s run. The other two, Chancellor and Thomas, were in a two-high safety alignment – rare for Seattle. Anquan Boldin, aligned narrowly in what defenses call a “nasty” split, cracked on Chris Clemons, leaving Jeremy Lane and Byron Maxwell at the point of attack facing two 49er pulling linemen.

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Following this play, Seattle should have allowed a touchdown. I’ll take Russell Wilson with more than three minutes, in continual four-down territory, needing a touchdown instead of needing a field goal with 21 seconds.