SANTA CLARA >> Brock Purdy was just 4 years old when a banner hung outside the 49ers’ locker room reading: “Win The West.”

That was in 2005, when first-year coach Mike Nolan knew the franchise’s quickest path back to relevancy was a division title, never mind that it took until 2011 to end the Niners’ playoff drought.

Now, after Purdy’s delivered back-to-back NFC West crowns to the 49ers, they need division wins more than, well, they just need them.

The 49ers (5-4) could be recapturing the playoff form after two months of bungling the role of reigning NFC champs. Sunday, they can improve to 2-2 in NFC West action and move into a share of first place with the Arizona Cardinals, so long as they beat the Seattle Seahawks (4-5) at Levi’s Stadium in a seventh straight meeting.

“There’s never a moment where we walk into this game going it’s going to be given to us or anything,” Purdy said.

The 49ers’ only divisional win this season came by outlasting the Seahawks 36-24 in a Thursday night, Oct. 10 visit to Seattle. More divisional drama awaits on Thursday, Dec. 12 when the Los Angeles Rams come to Levi’s Stadium, with the regular-season finale Jan. 5 or 6 in Arizona.

Here are five keys to victory for the 49ers:

1. CMC ENCORE VS. LBs >> Christian McCaffrey’s most impressive play in his season debut came when he exploited a mismatch against a linebacker (Lavonte David) for a 30-yard reception via Purdy’s heroic throw in the face of pressure. The 49ers will, and always have, seek similar mismatches. The Seahawks’ linebacker corps has undergone a radical, in-season makeover, with last month’s trade for Ernest Brown IV and Tuesday’s release of leading tackler Tyrel Dodson, who’ll be replaced by rookie Tyrice Knight.

McCaffrey winces at any thought the new-look Seahawks are easy prey and instead noted how maligned teams often pull out a surprising win under a recently named interim coach. (See: New Orleans Saints’ last Sunday).

The Seahawks’ duo of Bobby Wanger and Jordyn Brooks couldn’t stop McCaffrey last season: 259 yards and two touchdowns in the 49ers’ two wins. McCaffrey, since joining the 49ers two years ago, has run for over 100 yards in all four of his faceoffs against the Seahawks, including a January 2023 playoff opener. Neither Achilles flared up after his 56-snap, 107-yard debut in Tampa, so “I’ll keep rolling.”

2. OVERCOME SPECIAL TEAMS >> The 49ers’ season-long issues on special teams include a Seahawks’ kickoff return for a touchdown. More woes came last Sunday when Jake Moody’s three missed field goals (before his game-winner) and a muffed punt return caused by Darrell Luter.

Simply, the 49ers are the point they must expect and overcome another special-teams gaffe. Even tight end George Kittle noted that the desperate Seahawks could take chances such as a fake punt, on which they scored a touchdown in their 2021 game at Seattle.

3. COVERING DK, ETC. >> DK Metcalf got ejected in the Seahawks’ last matchup at Levi’s Stadium, once his tackle on Fred Warner’s interception led to a scuffle also involving Deommodore Lenoir, who ejected also with three minutes left in the 28-16 win.

In this rematch, Metcalf will return from a knee injury that cost him two games, and the 49ers’ cornerbacks will be led by Lenoir, who saunters in fresh off Wednesday’s contract extension (five years, $92 million).

This is not just Metcalf vs. Lenoir, however. Metcalf (35 receptions, 568 yards, three touchdowns) is part of a multi-prong corps that includes Jaxon Smith-Njigba (50-568-3) and Tyler Lockett (34-456-2).

4. PRESSURING SMITH >> Seattle ruled out starting center Connor Williams, thus inviting the 49ers’ defensive front to pressure up the gut against QB Geno Smith.

The 49ers need Nick Bosa to push through a hip injury like he did last game, when he endured 52 snaps with pain that was “the worst thing I’ve had to play through.” Resting rather than practicing this past week could be the tonic he needs to chase after Smith, who’s been sacked 28 times (and thrown 11 interceptions vs. 10 touchdown passes).

5. PROTECT PURDY >> Left tackle Trent Williams’ ankle and wrist injuries could leave Purdy’s blind side exposed, whether it’s Williams playing at less than 100 percent or backup Jaylon Moore drawing his first significant snaps this season. With seven fill-in starts his previous three seasons, Moore has played just 14 offensive snaps this season, nine coming in last month’s loss to Kansas City in which Williams got ejected for throwing a retaliatory punch.

Purdy’s increased mobility this season already has yielded career highs in yards (227) and carries (46). Sacked 18 times this year, six came in the 49ers’ Week 2 loss at Minnesota, where the Vikings deployed a confounding defensive scheme.

Seahawks coach Mike Macdonald’s scheme gave Purdy fits last year when Macdonald coordinated Baltimore’s defense (four interceptions), but produced 255 yards and three touchdowns with no turnovers and no sacks in the 49ers’ win at Seattle last month.