Now on their third-string quarterback, the San Francisco 49ers are nonetheless still rolling, as they have won six consecutive games following a loss to the Kansas City Chiefs back in Week 7. On Thursday night, the Niners travel north to take on their division rivals, the Seattle Seahawks, for the Week 15 edition of Thursday Night Football. 

San Francisco hasn't allowed more than 17 points since that aforementioned loss to the Chiefs, while it held Seattle to its worst offensive performance of the season when these two teams met for the first time this year. The Seahawks are surely looking to get back on track and jump-start their playoff hopes here, having now lost three of their last four games, including two to fellow NFC playoff hopefuls. 

Will the Niners keep rolling with their Brock Purdy at the helm, or will the Seahawks get back on track? We'll find out soon enough. In the meantime, here's a look at how you can watch the game. 

How to watch

Date: Thursday, Dec. 15 | Time: 8:20 p.m. ET
Location: Lumen Field (Seattle)
Stream: Amazon Prime Video   
Follow: CBS Sports App 
Odds: 49ers -3, O/U 43

When the 49ers have the ball

San Francisco just cannot stop getting bit by the injury bug. Deebo Samuel was the latest star to go down, though thankfully it seems like he will be able to return by the time the Niners get to the playoffs. He'll be absent from this game, though, robbing third-string quarterback Brock Purdy of one of his best weapons. Purdy himself is listed as questionable for the contest after he was limited in practices throughout the week due to rib and oblique injuries sustained during last week's victory over the Buccaneers

If Purdy cannot go and Josh Johnson gets the start under center, it's anybody's guess as to what this offense will look like. (Johnson is on his 14th NFL team, but he does technically have some experience in the Shanahan offense after spending time with the Niners and Jets in 2021.) We're going to operate under the assumption that Purdy will play, in which case we should see San Francisco run something resembling its usual offense. 

The Niners haven't changed much with Purdy under center in place of Jimmy Garoppolo, and in his last two appearances he has completed 41 of 58 passes for 395 yards, four touchdowns, and one interception. (He was 4 of 9 for 66 yards and a pick in garbage time against the Chiefs earlier this year.) Purdy's play-action rate is nearly identical to those posted by Garoppolo and Trey Lance earlier this season, and his time-to-throw distribution is remarkably similar to that of Garoppolo. He has been a bit more willing than Jimmy G to scramble when under pressure and more adventurous throwing the ball down the field and outside the numbers, but beyond that, you could be forgiven for not really noticing that the Niners had a different guy out there. 

Without Samuel, everything in this offense is going to revolve around Christian McCaffrey, though Brandon Aiyuk will operate as the top target on the perimeter. CMC has 41 touches for 299 yards and two scores over the Niners' last two games, and Shanahan has seemingly delighted in moving him around the formation to create advantageous matchups. The opportunity to do that should be there for him again on Thursday night against a Seattle defense that has yielded at least 161 rushing yards in each of last last four games and allowed the NFL's sixth-most receptions and third-most receiving yards to enemy running backs so far this season.

Seattle looks to have found a future star in cornerback Tariq Woolen, but the Seahawks' opponent in this contest is one of the least likely teams in the league to challenge his area of the field. The Shanahan offense is designed around middle-of-the-field passes before anything else, and between McCaffrey, Aiyuk, and George Kittle, they have a trio of weapons the Seahawks are not particularly well equipped to deal with. Barring the Seattle pass rush taking a significant (and surprising) step forward so it can dominate this game in the trenches, it's tough to see how the Seahawks will consistently get stops. They haven't against the likes of the Buccaneers, Raiders, Rams, and Panthers over the last four games, so there is no particular reason to think they will against the 49ers.

When the Seahawks have the ball

Way back in Week 2, the Seattle offense played its worst game of the season, against this 49ers defense. 

The Seahawks were held to just 216 total yards, 14 first downs, and seven points -- all season-low figures. They also turned the ball over three times, a season-high. It was Geno Smith's worst game of the year by adjusted net yards per attempt (which factors in touchdowns, interceptions, and yards last to sacks), and it's not particularly close. Smith completed 24 of his 30 attempts in that contest, but they were almost all close to the line of scrimmage, as Seattle had only two pass plays gain more than 12 yards.

The 49ers defense is designed to limit explosive plays in the passing game, and they have indeed allowed the fourth-fewest completions of 10 or more yards this season, and fifth-fewest of 20 or more yards. In all, opponents have created an explosive play on just 6.3% of their dropbacks against San Francisco, a rate that checks in higher than only that of the Cowboys, Eagles, Jets, and Saints. The Seahawks are a team that seeks those explosive gains quite often, but could find it difficult to access them against this defense. 

San Francisco is typically among the best defenses in the NFL at getting pressure with only four defenders rushing the passer, though that has been somewhat less true this year with Arik Armstead missing so much time. Still, the Niners rarely send extra rushmen after the opposing quarterback (20.8% blitz rate, per Tru Media), preferring instead to keep extra defenders in coverage. Seattle's offensive line has held up better than expected for a group starting two rookie tackles (Charles Cross and Abraham Lucas), and Smith has for the most part done a good job of navigating the pocket and getting the ball out quickly while still pushing it down the field. (He's been pressured at a slightly below league-average rate this season, per Tru Media.) 

That combination was difficult to find against the 49ers, though, due to their combination of pass rush and coverage. San Francisco plays aggressive on the perimeter, and has two of the best middle-of-the-field defenders in the league in linebackers Fred Warner and Dre Greenlaw. Charvarius Ward is also well-equipped to line up across from DK Metcalf due to his size and physicality and Deommodore Lenoir has fared quite as the Niners' second corner. 

Seattle has largely tried to Let Geno Cook this season, even in games where its backfield was healthy. With Kenneth Walker and DeeJay Dallas still banged up and having sat out a few days ago, and with Travis Homer more of a passing-down back anyway, it seems likely that the Seahawks will again lean on Smith to drive their offensive success. This is just not the right matchup for that strategy to find success. 

Prediction: 49ers 26, Seahawks 17