Every week is a must-win week. But I generally view Week 4 as a turning point in most leagues. A loss for an 0-3 or even 1-2 team might turn those managers into urgent or semi-urgent trading partners. Waiting for Jonathan Taylor's return is a luxury they can no longer easily afford. Sticking by a struggling Justin Fields (who I think will hit 20+ points today, for what that's worth) isn't justifiable.
On the flip side, a 3-0 or 2-1 team that wins can breathe a bit easier. Those managers can more easily invest in high-upside long-term plays. They can seize on the desperation of "win-now" opponents while bolstering their rosters for a playoff push.
Speaking of long-term plays, keep an eye on Jordan Mason. NFL.com's Ian Rapoport reportedly early this morning that Elijah Mitchell "is not expected to go." I've written about CMC's over-usage, which has put him on pace for 400+ touches. A two-touchdown favorite over Arizona, San Francisco probably is hoping to curtail their star RB's workload. A positive game script could/should give Mason 10+ touches. And given Mitchell's injury history, we shouldn't be surprised if a strong Mason showing pushes the younger RB alongside or even ahead of Mitchell on the depth chart.
Elsewhere, Jimmy G. is officially out. This is probably good new for Josh Jacobs, as Brian Hoyer and/or Aidan O'Connell might dump off more than usual. That said, despite the Chargers' beatable defense, L.A. should win this one more handily, meaning (I believe) Jacobs will need to do much of his damage in the first three quarters.
Some other notable updates: Deebo Samuel is expected to play. But with Jauan Jennings still doubtful, Ronnie Bell is an intriguing deep-league flyer. Derek Carr remains questionable. So is Tyler Higbee, though his playability appears more promising. Miles Sanders (questionable) should be out there without limitations -- aside from the limitations of the Panthers as a whole. And Marquise Brown (questionable) should be fine, though "fine" is relative on an Arizona team playing on the road versus the Niners.
And remember there's a game in London this morning. If it starts early in the morning based on your time zone, you might have woken up at halftime. Hopefully you set your lineup last night, or you don't have any of those guys on your roster.
Shifting to recommended 50/50 DraftKings DFS lineups, for the early slate (1:00pm Eastern), I'm going with Josh Allen, Zack Moss, D'Andre Swift, A.J. Brown, Tank Dell, Adam Thielen, Dalton Kincaid, DeAndre Hopkins, and the Eagles DST. It's a bit of point-chasing, which I dislike. But Dell and Thielen are priced so low, it's hard to ignore them. And keep an eye on Hopkins this week with Treylon Burks out. I could have gone Chig Okonkwo at TE (not a bad flyer), but prefer Kincaid because of (a) arguably more talent, and (b) probably a higher-scoring game. Eight points is nice, but I'm going boom-bust on the chance that Kincaid finds the end zone.
In the later-afternoon slate, I've got Justin Herbert, CMC, Jordan Mason, Keenan Allen, Joshua Palmer, Quentin Johnston, Gerald Everett, Jakobi Meyers, and the Cowboys DST. What?! How can I recommend five Chargers -- and none of them are Joshua Kelley? Well, like last week, I don't trust Kelley, even against a soft defense. Expect Isaiah Spiller and/or Elijah Dotson to get more work. This is also a golden opportunity for the rookie Johnston to get more acclimated to the NFL. The Chargers *should* win. Herbert *should* throw it 40+ times. There's enough potential volume to feed 3+ guys. So I'm betting that his top three wideouts, plus Everett, have a great shot at 60+ combined points (225+ yards and 3+ scores on 20+ receptions).
Good luck today.