The 49ers enter Week 5 with a few question marks, headlined by uncertainty at quarterback. A hobbled Jimmy Garoppolo is at risk of not finishing the game even if his start offers little fantasy appeal up against an Arizona pass defense that ranks No. 3 in DVOA. But if Jimmy G's calf injury keeps him out of Sunday's game, rookie Trey Lance would immediately become a top-10 fantasy QB.
Lance leads all quarterbacks in fantasy points per dropback this season, and while that's a bit misleading given he's come into certain goal-line situations, it also reveals his upside; the rookie put up 20+ fantasy points in one half last week while not playing very well. Lance was unquestionably erratic last week but will benefit greatly from a full set of starter reps in practice and a game plan designed for him. His rushing ability makes him extremely intriguing in fantasy leagues.
If Lance starts it should also help free up San Francisco's rushing attack, which is likely (but hardly certain) to be led by Trey Sermon, who played much better last week. Elijah Mitchell appears to be the better fit in Kyle Shanahan's system, but it's unclear how many snaps he'll be able to play Sunday while still limited in practice this week with a shoulder injury. It's a bit of a guessing game, but Sermon appears like the best San Francisco fantasy RB for Week 5, while Mitchell's the better long-term bet. It's terrific news all around for the 49ers offense that left tackle Trent Williams appears to have escaped a serious injury and is likely to suit up Sunday.
Deebo Samuel leads the NFL in receiving yards and continues to separate himself as San Francisco's clear WR1. In fact, Samuel has more yards after the catch this season than Amari Cooper, CeeDee Lamb, Calvin Ridley and DeAndre Hopkins have receiving yards. Samuel has emerged as a star and is a weekly top-10 fantasy wideout moving forward.
Meanwhile, Brandon Aiyuk belongs back on fantasy benches unfortunately after losing routes to Trent Sherfield once again last week. Aiyuk has too much potential to be dropped, and there's hope Lance's stronger arm results in more downfield throws (and maybe even some outside the numbers) and is a better fit. George Kittle is always a must fantasy start if active, but he's unlikely to be 100 percent Sunday.
The 49ers haven't lived up to their potential just yet, ranking No. 16 in DVOA while not pressuring the quarterback as much as expected. This week they face MVP candidate Kyler Murray, who's getting 9.5 YPA this season while helping the Cardinals average the most total yards per game (454.8). Murray has an argument to be fantasy's No. 1 QB in Week 5.
DeAndre Hopkins isn't going to live up to his ADP with Arizona spreading around targets so much (playing through a rib injury hasn't helped either), but he remains a constant in fantasy lineups and should benefit from injuries to San Francisco's secondary. Maxx Williams has emerged as a sleeper at a thin tight end position on a high-octane offense, while the rest of Arizona's receivers rotate and are tough to predict on a week-to-week basis. James Conner would become a potential top-five fantasy back should Chase Edmonds (shoulder) be forced to miss time.
Dalton Del Don has been with Yahoo Sports since 2013, covering fantasy football, baseball and basketball. He appears on multiple podcasts each week and currently resides in the Bay Area, where he is an avid fan of the Golden State Warriors and 49ers.