49ers vs. Seahawks prediction: Grab the points with Seattle on TNF

Several times throughout the year, NFL oddsmakers set lines that leave bettors scratching their heads. The 49ers vs. Seahawks Thursday Night Football game that kicks off Week 15 is a prime example.

San Francisco is absolutely rolling, winners of six straight games by an average of 18 points (including five double-digit routs of at least 13 points). During this run, the 49ers are 5-1 against the spread, covering the last four in a row.

Conversely, Seattle has followed a four-game SU and ATS winning streak with a 1-3 SU/0-4 ATS slump. The three losses were to opponents — Tampa Bay, Las Vegas and Carolina — that have a combined 16-23 record.

Also, when the Seahawks visited the Bay Area in Week 2, the 49ers punted them back to the Pacific Northwest with a 27-7 loss. (San Francisco easily covered as an 8.5-point favorite.)

So why are the Niners such a short road favorite Thursday in Seattle? Actually, we can think of a few good reasons.

That’s why we’re running away from most of the betting public with our 49ers vs. Seahawks prediction.

Note: Odds updated as of 9:45 a.m. on Dec. 15.

If you’ve placed more than a handful of wagers in your life, you know the old betting adage: If it looks like a trap and smells like a trap, it’s mostly likely a trap.

Well, this 49ers vs. Seahawks line sure seems like a trap.

All the obvious signs point to a comfortable win for San Francisco. But the not-so-obvious signs suggest otherwise.

First, new 49ers quarterback Brock Purdy has been outstanding since replacing Jimmy Garoppolo (broken leg) early in the first quarter of a Week 13 game against Miami. Purdy came off the bench and shredded the Dolphins while calmly guiding San Francisco to a 33-17 victory. At home.

Then after a full week of preparation, Purdy on Sunday led the Niners to 28 first-half points and played mistake-free football on the way to a 35-7 trouncing of Tom Brady and the Bucs. Again … at home.

On Thursday night, Purdy will make his first professional start on the road. And he will do so on a short week. And in one of the most hostile venues in the entire NFL. Against a division rival whose fans despise the 49ers.

Translation: This is not going to be an easy day at the office for 2022′s Mr. Irrelevant.

» READ MORE: Week 15 NFL lines: Eagles expected to keep rolling in Chicago vs. Bears

Making it all the more difficult? Purdy won’t have wide receiver Deebo Samuel on the field with him.

The 49ers’ uber-talented playmaker suffered ankle and leg injuries in last week’s game against Tampa. Samuel departed in the second quarter and is likely out the rest of the regular season.

He isn’t the only San Francisco player who is ailing. Running back Christian McCaffrey(questionable) continues to be limited in practice with a knee injury, and multiple defensive players on the two-deep roster are questionable (or worse).

Even Purdy himself is dealing with an oblique issue and listed as questionable. He’ll likely start, but if he can’t make it through the game, the quarterbacking chores fall to veteran journeyman Josh Johnson.

Seattle, meanwhile, is relatively healthy. In fact, not a single offensive starter was listed on Thursday’s injury report. That includes stud rookie running back Kenneth Walker III, who sat out Sunday’s 30-24 home loss to Carolina with a knee injury.

As for the Seahawks as a whole, look, there’s no excuse for giving up 30 points and losing at home to Sam Darnold and the Panthers. But that doesn’t erase the fact that Seattle has been in every game this season but one.

Yes, that “one” was in San Francisco. However, it was way back in Week 2. In 11 games since, the Seahawks have six wins along with five losses by point margins of 4, 7, 5, 6 (in overtime) and 6.

Seattle is also in full playoff desperation mode. So you know coach Pete Carroll will hold nothing back in this contest.

» READ MORE: Super Bowl odds: Eagles close the gap once again on Chiefs, Bills

Now, here’s what you might not know about Carroll: He does not often lose to the 49ers — especially twice in the same season.

In fact, even with their Week 2 road loss, the Seahawks are 17-4 against San Francisco since the 2012 season (playoffs included). That includes a 10-1 record at home (the lone blemish: a 26-21 loss in 2019).

Also, the Niners have swept a season series from Seattle just twice in two decades (2006 and 2011). However, only once did they win both games by more than a field goal (2006).

Two other historical footnotes to mention:

Will all this history repeat itself Thursday? We actually believe it will. Just to be safe, though, we’re grabbing the points with Seattle at BetMGM.

If you plan on doing the same, make sure to do so soon, as the line has dropped to 49ers -3 at several sportsbooks.

» READ MORE: Full sports betting coverage from The Philadelphia Inquirer

The Inquirer is not an online gambling operator, or a gambling site. We provide this information about sports betting for entertainment purposes only.