Most of the Week 18 slate in the NFL is likely to be lopsided, with plenty of teams playing backups and resting starters to get healthy before the playoffs get underway. However, there are still a few matchups with massive stakes on the line, none more than a matchup for the NFC West title on Saturday night.
After already playing each other once back in Week 1, the Seattle Seahawks and the San Francisco 49ers will do battle once again in Santa Clara to close out the regular season in Week 18. Not only will the winner lift the division crown in the toughest division in football, but they will get the No. 1 seed in the NFC and a first-round bye.
The 49ers won that first meeting over Seattle 17-13 in a defensive slugfest in Seattle on a late touchdown pass from Brock Purdy to Jake Tonges. That was the first game of the Sam Darnold-Klint Kubiak marriage in Seattle, and the offense has gotten a lot better since.
However, the other side of the ball is where both of these teams make their money. The 49ers have one of the most explosive offenses in the NFL, and the Seahawks boast one of the best defenses in the league led by Mike Macdonald.
How do each of those units make their hay, and who has the edge in Week 18?
Seattle can slow down Christian McCaffrey
When it comes to the 49ers offense, everything starts with star running back Christian McCaffrey. The Offensive Player of the Year candidate is the catalyst for everything this unit does on a weekly basis, and he can make an impact both on the ground or through the air.
However, this isn't your usual dominant 49ers running game that Kyle Shanahan is used to having. San Francisco doesn't have the same offensive line talent that it has had in some past years, and now Trent Williams may not play in this game due to a hamstring injury that he suffered in Week 17.
To this point in the season, McCaffrey ranks 30th in the NFL among qualified rushers in EPA per rush despite being one of the top total yardage-gainers due to the high volume that he gets.
Seattle's defense excels at just about everything, but it is especially good at stopping the run. Opponents are generating negative-0.18 EPA per rush allowed against the Seattle defense so far this season, the least efficient mark in the league by a wide margin. Seattle is able to achieve that number despite playing with light boxes on more than 42% off their snaps, so they aren't sacrificing coverage players to stop the run.
That ties into the second way that the Seahawks will be tasked with slowing down McCaffrey: in the passing game. The 49ers running back is one of the top pass-catchers in the league regardless of position and currently leads the Niners in targets (122), catches (96) and receiving yards (890).
The 49ers use McCaffrey in all kinds of ways in the passing game, lining him up all over the formation to try to create matchup advantages. No matter where he is on the field, he and Purdy have built great chemistry on option routes.
From a personnel standpoint, the Seahawks have the right kinds of players to contain McCaffrey. Ernest Jones IV is one of the best coverage linebackers in the league, and nickelback Nick Emmanwori is a freak athlete that can stick with the shifty running back. However, the Seahawks have only been average this season against backfield targets according to Next Gen Stats, ranking 13th in the league in EPA per play allowed on those plays.
In the first meeting, McCaffrey didn't have a lot of success on the ground, accumulating just 69 yards on 22 carries. However, he caught nine of his 10 targets for 73 yards and was a factor in the passing game throughout.
Emmanwori wasn't a big part of this Seahawks defense in that meeting, so his presence on the field should help Seattle contain McCaffrey even better this time around.
Will Brock Purdy's prowess under pressure hold up?
Brock Purdy has only played in eight games this season due to a turf toe injury that lingered during the first half of the season, but he has been one of the best quarterbacks in the NFL when healthy. In addition to the easy buttons he gets from Kyle Shanahan's system, Purdy has eliminated a lot of negative plays and is creating a lot of big plays out-of-structure for the 49ers.
He is coming off of his two best games, wins over the Colts and Bears, where he scored 10 total touchdowns and turned the ball over just one time. The Colts and Bears defenses both leave a little to be desired, so the challenge will be much stiffer on Saturday against an elite Seattle unit.
One of the main themes from those two games was the amount of time Purdy had to operate in the pocket. The Bears and the Colts both have pretty toothless pass rush groups, and Purdy was sacked just once in each of those games while maintaining a pressure rate under 25%.
That will be hard to maintain against a Seahawks defense that ranks fourth in the NFL with a 39.1% pressure rate. Seattle doesn't blitz a lot, but Mike Macdonald is a master at getting his guys free with pre-snap alignment, and the Seahawks have a talented defensive line that can win individual matchups.
Purdy has been one of the best quarterbacks in the league when under pressure this season, even if he hasn't had to face a whole lot of it in the last few weeks. He has taken just eight sacks in 98 pressured dropbacks this year and boasts the fourth-highest EPA per dropback on those plays according to Next Gen Stats.
In Week 1, the Seahawks pressured Purdy on an incredible 60.5% of his dropbacks. The 49ers quarterback completed 13-of-20 passes on those plays for 126 yards and a touchdown, but he also tossed two interceptions. It's clear that the Seattle pass rush had a big impact on the young signal-caller in that game, and they will have to do so again in Week 18.
With Williams likely out after not practicing on Wednesday and Thursday, it will be even harder for the 49ers to block this Seattle defensive line in this game. If Purdy has another erratic day against the pressure like he did in Week 1, the Seahawks offense has likely improved enough to get the win. If Purdy can dissect the pressure, then San Francisco should have a good shot at securing the top seed.
