Jamaal Charles has something left in the tank. (Mark Konezny/USA Today Sports)

The waiver wire hasn’t yielded much fantasy fruit in September. We’ve had high-profile injuries — David Johnson, Greg Olsen, Allen Robinson, Andrew Luck — but no amazing answers as replacements. Tarik Cohen has been good, Chris Thompson has been good, but we haven’t seen the league-changing stars-to-be that will inevitably come. I know it can be frustrating if you’re sitting on a big pile of FAAB money or if you hold your league’s No. 1 waiver spot, feeling like you’re letting potential adds go by while your active roster struggles. But in most cases, that’s what I’d do: If the first half of the NFL season doesn’t see a landscape-altering potential waiver add, it’ll be the first time ever. 

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Must-startJoe Mixon, RB, Cincinnati

Okay, maybe “must” is a little strong. I’m fine if you want to wait one more week on Mixon, because the Bengals’ running game hasn’t hit its stride. But the times, they are a’changing. Yes, Jeremy Hill started Week 3 against the Packers, but Mixon played 34 snaps, while Hill played 14 and Gio Bernard played 13. When the Bengals were trying to nurse a lead late, Mixon did his best work: five carries on a fourth-quarter drive during which the Packers knew what was coming, and Mixon flashed his combo of power, speed and elusiveness. He did fall down on a crucial third-and-one before Andy Dalton could hand him the ball, leading to a Bengals field goal that ultimately kept it a one-score game. But soon enough Cincinnati will stop fooling itself and use Mixon over Hill as the rule, with Bernard mixing in. And this week against the Browns might be a nice time for an unveiling. 

Must-startWillie Snead, WR, New Orleans

Snead will return from his three-game suspension for an offseason DWI on Sunday against the Dolphins in London. If you’ve been holding onto him, get him in your lineup. If you were worried that Ted Ginn Jr. would ensconce himself as Drew Brees’s No. 2 receiver, I think you’re okay: Ginn did score a touchdown Sunday, but in his first work as a Saint he has averaged three catches and 40 yards per game. Snead isn’t fast and isn’t really even all that quick by NFL standards, but he’s a smart and technical route-runner and joins a New Orleans offense that — last week’s bizarro romp over the Panthers notwithstanding — figures to need to score points to stay competitive. Snead is just fine as your No. 3 fantasy wideout. 

Must-add: Jamaal Charles, RB, Denver

Once again, “must” is a relative term. The waiver wire isn’t all that hospitable this week, which is why I’m reaching for a blast from the past. Charles is available in about two-thirds of Yahoo leagues, and I wouldn’t give up much FAAB money or waste a top waiver claim on him, but for the first time Sunday he started to look like the player we remember from his many fun years with the Chiefs. The roles C.J. Anderson and Charles filled were unchanged against Buffalo — Anderson was still on the field twice as much as Charles — but as Denver’s coaches get a look at the Week 3 film, it’s possible they’ll decide to tilt toward a more even workload. Anderson has terrific balance, power and leg drive, but he’s relatively slow. If Charles can really get to and through defensive holes like he used to, he’s got a chance to stay on the field more. 

Trade for: DeVante Parker, WR, Miami

I mentioned Parker as a “must-start” in last week’s column, and it almost backfired: The Dolphins were disastrous in their trip to Gotham, and Parker racked up one catch for minus-one yard before a few late-game garbage-time drives made the afternoon look respectable. No question, coming out of perhaps the NFL’s most embarrassing Week 3 loss, the bloom is off Miami’s rose. That’s a good time to pounce. I know the Dolphins would prefer to be a running team behind Jay Ajayi, and I know that by investing in Parker you’re also investing in Jay Cutler by proxy. But I said it last week: Parker is on the verge of becoming a force that no game plan or quarterback can suppress. Use the Dolphins’ terrible Week 3 performance and Parker’s garbage-time results as a way to pry him loose. If the Parker owner in your league is hot and bothered for Tarik Cohen or Chris Carson, perfect. Make the move. 

Don’t-addCase Keenum, QB, Minnesota

Don’t get clever. Keenum was legit awesome against the Buccaneers, throwing for a career-high 369 yards, three touchdowns and no interceptions. Stefon Diggs made a series of great plays for him, and Adam Thielen caught a long one early … but I remain skeptical. It’s lame to blame defensive injuries, but the Buccaneers were missing maybe their four best defensive players by game’s end Sunday. More significantly: I’ve seen this movie before. Remember when Keenum came up with the Texans, and people tried to sell him to you as the next Tony Romo? Remember when he took over the Rams’ starting job after it turned out Nick Foles couldn’t play? The more sunshine Keenum’s game gets, the more obvious it is that he doesn’t see the field well, doesn’t have a power arm and doesn’t throw accurately. The best we can hope for is that, for however long Sam Bradford is out, Keenum keeps Diggs and Thielen in clover. As a fantasy option himself, no. 

Christopher Harris runs HarrisFootball.com, where you can find more info on the “Harris Football Podcast,” with new episodes every weekday.)