The San Francisco 49ers will face the Arizona Cardinals in Week 18. Here’s fantasy football start-sit advice for every 49ers and Cardinals skill player who has the potential to make a fantasy impact during the game.
Looking for more lineup advice? Head over to our Week 18 Fantasy Start-Sit Cheat Sheet, where we cover every fantasy-relevant player in every game.
San Francisco 49ers Week 18 Start-Sit Advice
Brock Purdy, QB
Updated at 2:55 ET on Sunday, January 5
Purdy is inactive for today's game.
In Weeks 1-16, we didn’t have a single game where a QB threw for 350 yards and three touchdowns while also rushing for a score — Joe Burrow and Purdy both did it in Week 17.
Last week was fun — until it wasn’t. A late elbow injury resulted in Purdy missing sometime late in the loss to the Lions, and he will not play in Week 18. Instead, Joshua Dobbs will get the start under center.
This year, Purdy did just fine for himself, given the circumstances. With his top skill-position teammates falling like flies, he posted nine top-12 finishes.
I like his combination of athleticism and YAC teammates, which could land him on many of my wait-on-a-quarterback rosters next season.
Joshua Dobbs QB
Joshua Dobbs will get the spot start, with Brock Purdy dealing with an elbow injury suffered late in Week 17’s loss to the Lions. He completed three of his four passes for 34 yards and added a seven-yard rushing score late against the Lions on Monday night, showcasing the versatility that we’ve had an interest in when he has been pressed into duty in the past.
Personally, I’m in no hurry to start him in a meaningless game, but if you’re going to stream the position, he’s as viable as any, provided that the 49ers elect to play their regulars.
Dobbs averages 5.8 yards per pass for his career and had as many touchdown passes as interceptions with the Vikings last season. There is some rushing upside in his profile, but not so much that you need to move heaven and earth to get access to it.
Isaac Guerendo, RB
Updated at 2:55 ET on Sunday, January 5
Guerendo is active for today's game.
Issac Guerendo was able to suit up on Monday night, and as expected, was the only 49ers running back to get handed the ball. He finished with nine carries for 34 yards, but a 40-yard catch on a perfect throw from Brock Purdy helped save the day (four catches for 65 yards).
Christian McCaffrey is obviously the man in town, but I like what I’ve seen from Guerendo this season, and at the very least, he should be a prioritized handcuff in 2025.
Jordan Mason ran for 89 yards on 14 carries in Week 5 against the Cardinals, a level of production that I think is possible for Guerendo this week. The quality of his touches is currently a question mark with Purdy banged up, but I think the sheer volume should be enough to get him into your lineup, with the name under center further dictating the upside case.
Deebo Samuel Sr., WR
Week 18 Status: OUT
Last week was Samuel’s second (healthy) half this season without a single target. While he scored on his only “target” of the game, that was nothing more than a run play that happened to feature a forward lateral.
He has multiple rush attempts in four straight games, and even if he were playing, that wouldn’t have been enough to keep him ranked as a fantasy starter this week.
Samuel saw 16 targets in the two weeks before last week’s struggles, but that came on the heels of earning just 12 looks over a three-game stretch. I was hopeful that he’d establish some level of consistent role in this passing attack with Brandon Aiyuk out, but that’s been more Jauan Jennings than anything.
At this point, Samuel’s name carries more value than his on-field production. We’ll see if he is able to rebound next season.
Jauan Jennings, WR
With Purdy not playing this week, I’ll be looking to bench Jauan Jennings. Josh Dobbs (5.8 yards per attempt with 15 touchdowns and 13 interceptions across 22 career appearances) is the next man up, and with Jennings on a very friendly deal for one more season, why put him in harm’s way?
If Purdy were suiting up, Jennings would have slid in as a viable Flex option in PPR leagues, thanks to him averaging 8.4 targets per game since the beginning of November. If we are operating under the assumption that Brandon Aiyuk has played his final game with this organization, Jennings is going to be a hot commodity next draft season – this offense is still a talented one when near full strength.
George Kittle, TE
Updated at 2:55 ET on Sunday, January 5
Kittle is active for today's game.
George Kittle earned a 37.5% target share in Week 5 against these Cardinals (8-64-1 stat line) and his role seems stable, even with the 49ers simply playing out the string of the season.
It’s been a weird relationship for fantasy managers and Kittle over the past two seasons – his ceiling has proven to be nothing short of elite, but the floor can be maddening. This year, however, we got more consistency. It stands to reason that 2025 could look a lot like 2024.
Kittle is 31 years old, and that introduces some age-curve concerns, but I expect to be in line with the consensus on him this summer. That means I’ll be investing should my roster construction point in that direction.
Arizona Cardinals Week 18 Start-Sit Advice
Kyler Murray, QB
This season hasn’t gone nearly the way fantasy managers had hoped for Kyler Murray, and Saturday was a pretty good reflection of that.
Despite 52 opportunities (pass + rush attempts) against a reasonably vulnerable Rams defense, Murray managed just 16 fantasy points. For the season as a whole, he has more sub-12-point games (five) than games with 21+ (four), something that I would have told you was close to impossible if you gave me the facts of him completing 68.6% of his passes while averaging a career-high 7.3 yards per carry.
Despite those rate stats, it’s been the “hows” of him getting those numbers that have been the problem, and that is what scares me for 2025. His aDOT this season is a career-low 6.9 yards and, more impactful for our purposes, the rushing volume is in steady decline.
Kyler Murray, completions per rush attempt by season:
- 2020: 2.82
- 2021: 3.77
- 2022: 3.87
- 2023: 4.00
- 2024: 4.63
Murray has at least three more years on his contract, and this is the sort of usage that doesn’t reverse with age. The Marvin Harrison Jr. connection should develop with time, and Trey McBride is a special playmaker, but if we are trending four-ish carries per game as opposed to the 6.7 he averaged through his first season, we need to rethink the upside case significantly.
As for Week 18, Murray relied on his legs to produce in the Week 5 meeting with the 49ers (83 rush yards and a touchdown), something that I’m not sure sticks. The Cardinals have no motivation this week, but without a developmental QB to give snaps to on the roster, I’m projecting a full game from Murray; that’s enough to land him inside my top 10, a ranking I’m not positive he enters next season with.
James Conner, RB
Updated at 2:55 ET on Sunday, January 5
Conner is out for today's game.
James Conner entered Week 17 banged up and never returned to action (knee) after exiting in the first half of Saturday’s loss in Los Angeles. Postgame reporting suggested that the veteran back was able and willing to return to the game while the coaching staff ruled against it (Michael Carter finished with 70 yards on 13 carries).
If this were in the middle of the season, I’d be fine betting on an experienced back like this who knows his body. But at this point in a lost season, I believe that the cautious approach we saw last week repeats this week.
Conner has over 1,600 touches for his career, and that’s a concern. But with volume still in his favor and him posting his best points-per-touch season since 2021, there’s reason to think that he’s a viable option entering 2025.
I’m pessimistic that we get much in the way of value this weekend, but he is one of the long-in-the-tooth RBs that I’ll be willing to have shares of next year.
Trey Benson, RB
Trey Benson was placed on injured reserve on December 31, which will end his rookie season.
There’s certainly a case to be made for Benson to be among the top five handcuff running backs next season, and I’ll happily scoop up shares late if the opportunity presents itself.
Marvin Harrison Jr., WR
To call this season a disappointment numerically for Marvin Harrison Jr. would be an understatement, to say the least. It would be fun to see him finish with exactly seven catches and a score this week to equal the output of his dad in those categories during his rookie season in 1996 with the Colts, but that’s not exactly what we had in mind.
Mirroring his father long-term would be great, but based on where the expectations were entering this season, matching single-year marks from 28 years ago isn’t exactly ideal.
The Cardinals have lost five of six games, and Harrison hasn’t reached expectations based on his target diet in a single one of them. The 49ers held him to 36 yards on a 23.3% target share in Week 5, and that doesn’t exactly fuel optimism for me entering this game.
On the bright side, Arizona is motivated to send the rookie into the offseason on a positive note. He’s seen at least eight targets in four of his past five, and the three Lions who saw at least that many looks against San Francisco on Monday night all scored.
Harrison slips just inside my top 30 this week, ahead of the more veteran receivers like Calvin Ridley, Adam Thielen, and Keenan Allen, who are also playing in games that mean nothing for their team.
Michael Wilson, WR
Updated at 2:55 ET on Sunday, January 5
Wilson is inactive for today's game.
Michael Wilson led the Cardinals in receiving in the Week 5 game in San Francisco, racking up 78 yards on a 20% target share. If there is one member of this Arizona passing game who could use a confidence boost entering 2025, it’s Wilson.
Trey McBride has had a phenomenal season, and Marvin Harrison Jr. isn’t going to struggle to believe in himself anytime soon. Wilson’s counting numbers weren’t there on his six targets, but with 11.6 expected PPR points, we aren’t far off of him being at least worthy of Flex consideration
This is the sort of profile I don’t mind betting on again at a discount next season, but not in Week 18, given that he has reached fantasy expectations just once twice in his past eight games, both of which came against the same opponent (Seattle) – the good news there is that as long as he is a Cardinal, the Seahawks will be on the schedule twice a season!
Trey McBride, TE
Trey McBride is a special player and his Week 17 performance was just the latest example.
I have him penciled in for my TE1 overall next season. That may be a little more aggressive than most, there’s no debating that he is a Tier 1 option at the position.
Trey McBride recorded his third game with 12+ catches in a game this season – he’s the first TE EVER to do that and just the 11th player to do so.
A fourth game would tie him atop the all-time list for such games in a single season with Cris Carter (1995) & CeeDee Lamb (2023). pic.twitter.com/CD1SniejFF
— Pro Football Network (@PFN365) December 29, 2024
The Cardinals may not need this game, but there are no signs that they will rest their star tight end. With him proving to be as much of a reception vacuum as anyone at the position (30% target share in the Week 5 meeting with these 49ers), he’s a top-five play.
McBride has 170 catches over his past 25 games and could become the NFL’s first tight end with a pair of 100-catch seasons over his first four years in the league.