The upside: Even the worst defeats tend to feature a bright spot or two.
The Seahawks scored 17 fourth-quarter points to make the game close heading into the final five minutes.
Rookie receiver Doug Baldwin, an undrafted free agent from Stanford, caught four passes for 83 yards, including one for a 55-yard touchdown in the fourth quarter. Baldwin also caught a second-quarter pass for a 12-yard gain on third-and-9.
Receiver Golden Tate, looking to build on a strong finish to the preseason, caught an 8-yard scoring pass for Seattle's first points.
Seattle's defense held the 49ers to 209 total yards. The team has now allowed only 398 total yards to its last two regular-season opponents, having held St. Louis to 189 yards in Week 17. The 209- and 189-yard totals are the Seahawks' lowest since holding Jacksonville to 199 yards during a 2009 game.
The Seahawks allowed only one third-down conversion in 12 chances for the 49ers. San Francisco finished with only 12 first downs overall.
Jon Ryan had a 77-yard punt and one other punt downed inside the 20-yard line.
Offseason additions to the defensive line appeared to play well. Alan Branch had a strong game as part of the Seahawks' stout run defense. Anthony Hargrove, signed only Saturday, impressed with a tackle for loss. Branch, Hargrove, Brandon Mebane and Red Bryant gave the Seahawks a strong wall against the run, holding Frank Gore to 2.7 yards per carry.
Some of the team's young defensive players also stood out, notably free safety Earl Thomas.
Quarterback Tarvaris Jackson threw no interceptions of consequence. The one he threw right before halftime on a Hail Mary hurt his stats without hurting his team.
Looking ahead: The Seahawks visit the Pittsburgh Steelers in Week 2.