The Seattle Seahawks and San Francisco 49ers face off Saturday night in a battle for the NFC West crown and the conference’s top seed.

An intriguing matchup will be key for Seahawks’ D against Niners

It’ll also be a meeting of one of this year’s best defenses against a red-hot San Francisco offense. Brock Purdy has 10 touchdowns in the last two weeks, and the 49ers are averaging 42 points per game over their last three. Meanwhile, the Seahawks’ defense has limited opposing offenses to the second-fewest points per game and hasn’t allowed a 100-yard rusher in 25 consecutive games.

But you’ll hear plenty about those two sides of the ball. That’s why your two numbers that matter for Week 18 tell the story of the Seahawks’ offense and the 49ers’ defense.

Your first number that matters is… 30

You know the Achilles heel of this Seahawks offense. It’s giveaways. It could end up costing them in the playoffs. With the spotlight on a phenomenal season for Seattle’s defense, it’s easy to feel like Seattle’s offense is, well, anemic. Slow starts, interceptions and fumbles, an inconsistent run game…

But not so fast. It may not be the single greatest strength of this team, but Seattle’s offense is tied for the most 30-point games in the NFL this year (8) and has the most 35-plus-point games in the league (6). The 49ers’ defense is the fifth-worst against the pass Seattle has faced, and the Seahawks have scored 30-plus points against three of those other four teams. And while some of the scoring has been a product of defense and special teams, consider that this year’s Seahawks have scored 470 points – the most of any Seahawks team ever, beating the 2020 squad (that was also the last time this team won the NFC West).

The Seahawks need to score earlier and more often in the first half. It’s risky to fall behind in the postseason. But for now, they can at least hang their hat on being the highest-scoring third quarter offense this year.

Your next number that matters is… 18

The 49ers’ defense has made key plays. A pick-six of Philip Rivers in a Monday night win over the Colts, key stops late of Caleb Williams and a surging Bears offense on Sunday night.

But overall, they’ve struggled to get to the quarterback. They’re last in sacks, with just 18 this season. They’ve registered fewer pressures than the Raiders. Personnel changes are a massive part of that story – it’s tough to be stellar without your two best defenders on the field — but a struggling defense is an underrated part of the 49ers’ season. It’s wildly impressive that they’ve been able to fight for the top seed without Nick Bosa and Fred Warner, but it’s also meant there’s another obstacle to overcome: getting to a Super Bowl with a bottom-third defense. You’d assume Robert Saleh’s group would try to blitz more often in this one, considering Darnold’s struggles against mounting pressure this season. But fail to get home with that pressure and you risk a massive day from Jaxon Smith-Njigba, who had 124 yards in their Week 1 meeting.

More on the Seattle Seahawks

• Bump: It’s the Seattle Seahawks O-line’s time to shine vs 49ers
• The Reset: The reasons the Seattle Seahawks will beat the 49ers
• Seahawks-49ers Injury Report: Shaheed to play; Cross ruled out
• Stacy Rost: Defense wins championships? Seahawks are counting on it
• Daniel Jeremiah: What’s changed since Seahawks’ Week 1 loss to 49ers