If there were any lingering questions about the legitimacy of Seattle following its back-to-back blowout wins of Buffalo and Arizona, they were answered Sunday night.

A week after the 49ers delivered perhaps their most impressive performance of the year -- going to New England and beating the Patriots -- the Seahawks one-upped them with a resounding win against their division rival in Seattle.

If the Rookie of the Year conversation doesn’t begin with Seahawks QB Russell Wilson at this point, something might be wrong. Although Andrew Luck and Robert Griffin III have worthy resumes too, Wilson’s play has turned Seattle from a team with a good defense into one that’s just as scary offensively.

"He hasn't changed,” Seattle coach Pete Carroll said. “He's won us over. Really. We've changed. He's the same." 

Wilson was 15 of 21 for four TDs and an INT against San Francisco and has thrown 25 TD passes -- one shy of Peyton Manning’s NFL rookie record. It seems like a safe bet that the record will fall next week when Seattle hosts St. Louis to finish the regular season.

For San Francisco, the absence of DE Justin Smith was glaring. Since Smith left last week’s game at New England with an elbow injury, LB Aldon Smith has been rendered largely ineffective. His departure last week seemingly coincided with the Patriots 28-point run, and the 49ers’ defensive inefficiencies continued against Seattle.

When the game turned: Seattle S Kam Chancellor blew up 49ers TE Vernon Davis late in the first quarter near the goal line with the Seahawks leading 14-0. He was flagged for hitting a defenseless receiver, although replay shows it was a clean hit. Following the penalty, the 49ers couldn’t punch it in and a chip-shot field goal from David Akers was blocked and returned 90 yards for a TD by Richard Sherman. Game over.

Highlight moments: Marshawn Lynch set the tone with a 24-yard touchdown run early as the Seahawks got on the scoreboard less than 90 seconds into the game. After that, it was one highlight after the next for Seattle, which handed the 49ers their biggest loss in the Jim Harbaugh era. … Sherman’s 90-yard FG block return was key. … QB Russell Wilson showed nice touch on TD passes to Anthony McCoy (6 yards) and two to Doug Baldwin (4 and 6 yards).

Top-shelf performances:

•  Seattle QB Wilson -- 15 of 21 for 171 yards, 4 TD, INT

•  Seattle RB Lynch -- 26 carries for 111 yards, TD

•  Seattle WR Baldwin -- 4 catches, 53 yards, 2 TD

•  49ers LB Navorro Bowman -- 16 tackles, TFL

What they said about the atmosphere at CenturyLink field:

  • Seattle coach Pete Carroll -- “That crowd was crazy tonight. They deserve a playoff team and they got it.”
  • 49ers QB Colin Kaepernick -- “It’s loud in other stadiums, too. It’s something you have to get used to playing on the road." 

Numbers you should know: Seattle’s 150 points in its last three games are more than it scored in the entire 1992 season. San Francisco’s six-game prime-time win streak ended with the loss, and Seattle extended its home winning streak to seven.

Injury update: 49ers – TE Davis (concussion), WR Mario Manningham (knee) and DL Will Tukuafu (back) all left the game and did not return. Their status remains unclear, but Manningham reportedly left the locker room on crutches. According to Comcast SportsNet Bay Area, the X-rays showed no break, but the 49ers are reportedly worried about ligament damage. DE Justin Smith did not play and Harbaugh did not make it clear if he’s expected back for the playoffs. Seahawks -- No injuries of note. 

Going forward: 49ers -- San Francisco will host Arizona next week and will clinch the NFC West title with a win. Seahawks -- Seattle closes the regular season at home against St. Louis with its sights set on the No. 5 seed in the NFC playoffs. Seattle can win the NFC West with a win and a 49ers' loss.

Follow 49ers reporter Kyle Bonagura on Twitter @CBS49ers and @KyleBonagura.

For more up-to-the-minute news and analysis from Seahawks blogger John Breech follow@JohnBreech and @CBSSeahawks.