Fantasy Baseball Buy-Lows? Unlucky Star Players (Week 21)

August 19, 2026

Frank's fantasy baseball buy-lows, breakouts, trade candidates to target for Week 21 in 2026. These unlucky players are underperforming early for fantasy baseball.

Welcome back, RotoBallers, to another edition of Buy-Low Candidates for Week 21 of the fantasy baseball season. Each week of the fantasy baseball season, we look at struggling star players who are top buy-low candidates. Last week's list included names like Tarik Skubal, Gunnar Henderson, JJ Wetherholt, and Trevor Rogers.

For this week, we will dive into four more buy-low candidates. These four players have been struggling recently, but things should turn around for them within the next few weeks. It's best to acquire them now while their fantasy value is at rock bottom. Each of these players is rostered in over 60% of Yahoo! leagues and should be viewed as trade targets.

Let's dive into the four best buy-low candidates right now for Week 21. This includes two hitters and two pitchers. Some of these players will be harder to acquire than others, but the key is to use their recent rough patch as a sales pitch. With that in mind, read on to find out why I'm trying to buy low on Hunter Brown, Kevin McGonigle, Tanner Bibee, and Salvador Perez. Each of these players won't be hard to acquire.

Hunter Brown, SP, Houston Astros (95% Rostered)

Brown has been inconsistent since returning from injury, looking nowhere near the ace that we saw last season. The 27-year-old righty has a 3.67 ERA and a 1.30 WHIP with a 24.7% strikeout rate and a 13.7% walk rate. The walk rate sticks out like a sore thumb here, as it's a major increase from the 7.8% rate we saw last year.

It makes sense to see Brown struggle with command given that he had such a long layoff. Perhaps he just needs time to get in a groove. But in his last outing, he had five walks in only five innings against the Mariners. Brown has issued at least two free passes in four consecutive outings.

That's why the timing is right to try to swoop him from your leaguemates to try to buy low. Once Brown gets his command back, which feels like it's only a matter of time, he's likely to look like a frontline starter once again. We can see the signs in his underlying metrics, as he still has a 3.84 xERA despite the poor command.

Hunter Brown, Wicked Knuckle Curves. 🤢 pic.twitter.com/IHiAC8QAua

— Rob Friedman (@PitchingNinja) August 17, 2026

While Brown's strikeout rate is down from last year, 24.7% is still above average. It's more impressive that he has this because of the extended absence. His arsenal still looks strong, as highlighted by a 103 Stuff+, which is not too far off from last year (105 Stuff+).

There's a chance that your leaguemate who rosters Brown has grown frustrated with the Astros' ace, especially since they had to wait a while for him to return. With that in mind, I'd try to offer someone like Drew Rasmussen to get Brown plus one more piece, like a newly minted closer such as Kodai Senga or a temporary closer like Tanner Scott.

Kevin McGonigle, 3B/SS, Detroit Tigers (93% Rostered)

McGonigle came into the 2026 MLB season as the consensus No. 2 prospect in all of baseball, behind Pirates' shortstop Konnor Griffin. From a real-life standpoint, McGonigle has certainly lived up to the hype, showing advanced plate discipline. The 22-year-old is currently slashing .282/.386/.424 with 13 home runs and 12 stolen bases in 547 plate appearances.

This looks like a future star at the plate. Watching a rookie put up a 14.1% walk rate and 14.1% strikeout rate is extremely impressive. He's been worth 4.7 WAR this year, immediately establishing himself as an important piece for the Tigers.

Kevin McGonigle doubles the @Tigers lead 💪 pic.twitter.com/IUBNQPoUxr

— MLB (@MLB) August 17, 2026

With a super talented player like this, we often see them save their best work for the end of the year. This is when they've fully acclimated to big-league pitching. Since the Tigers are in the thick of the AL Wild Card race, there's a chance that McGonigle can step it up with a monster September, right in time for the fantasy playoffs.

That's why I love the idea of trying to buy low on him. While his numbers are rock-solid from a fantasy standpoint, the overall profile, one with patience and contact ability, signals that this is a player ready to take off.

I recommend trying to trade a middle infielder with more power and speed this season, since that's a bit flashier. Why not try to trade Zach Neto for McGonigle and another piece? Neto is striking out a lot and hurting your batting average, but his big name may get the deal done for you.

Tanner Bibee, SP, Cleveland Guardians (79% Rostered)

Bibee has been a dependable innings-eater for the Guardians, putting up a 4.01 ERA and a 1.15 WHIP with a 19.1% strikeout rate and a 7.0% walk rate in 150.1 innings. While the K% is underwhelming, he's shown some improvement there, including a 10-strikeout outing against the Mets on August 5th.

In his last 14 starts, Bibee has a 3.61 ERA and a 1.03 WHIP in 87.1 innings. With the Guardians still in playoff contention, Bibee is in a position where he can get you wins.

The best part about trying to trade for Bibee is that he's unlikely to cost you much. He's not a flashy pitcher, as we can see with the underwhelming strikeout rate. To that end, you may be able to flip someone like Nick Martinez and another asset to bring in Bibee.

It's valuable to have these types of innings-eaters to round out your rotation, especially when you're trying to make up ground in wins, which is a tough category. With that in mind, Bibee can make an impact here for you, and he'll come at a reasonable cost, so try to make the move.

Salvador Perez, C/1B, Kansas City Royals (76% Rostered)

Perez has several years of strong production, especially in the power department. But the 36-year-old is finally showing major signs of decline this season, as highlighted by a .215/.261/.365 slash with 16 home runs in 484 plate appearances. His barrel rate has plummeted from 14.7% to 9.5%, so he's not hitting the ball nearly as hard.

However, there's some light at the end of the tunnel here. The Royals are starting to heat up at the plate. They just got Vinnie Pasquantino back, while Maikel Garcia is almost ready to return. That strengthens the lineup in a major way, which means that Perez will be in a good spot for run production, especially since he hits in the heart of the order.

Given Perez's lackluster numbers for the season, you should be able to acquire him with ease. The only problem you may run into is that your leaguemate trading him away may want a catcher in return.

If you need some power, it may make sense to flip someone like Gabriel Moreno for Perez and another piece to improve your roster elsewhere. I have a feeling that we're going to see the veteran turn back the clock in September, with the Royals starting to get healthy and play better baseball.

Remember, Kauffman Stadium is more of a hitter's park after they moved the fences in, so it's not a stretch to think that we can see a power binge from Perez in September, just in time to help you out down the stretch, en route to a fantasy championship.

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