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Frank looks at three sneaky fantasy baseball waiver wire pickups for starting pitchers in Week 21 (2026) on hot streaks, and sees if they can sustain their success.
Welcome, RotoBallers, to another edition of our Sneaky Starting Pitcher Waiver Wire Column for Week 21 of the fantasy baseball season. Every week of the fantasy baseball season, we look at three pitchers who are in a nice rhythm and determine whether these pitchers can sustain their recent strong production.
For this week, we will look at three red-hot pitchers. Each of these pitchers has found their groove recently, beginning to emerge as reliable fantasy options. They're pretty widely available across all formats, rostered in fewer than 30% of Yahoo leagues.
This list includes three names that can be easily picked up, including two veteran right-handers and a lefty with strikeout upside. With that in mind, let's take a look at these three pitchers for Week 21 of the fantasy baseball season.
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Adrian Houser, San Francisco Giants
2% Rostered (Yahoo)
Adrian Houser has a 4.28 ERA and a 1.32 WHIP in 103 innings this season. This includes an underwhelming 15.8% strikeout rate and a 7.2% walk rate. His underlying metrics aren't good, either, as highlighted by a 4.98 xERA.
However, we've seen Houser turn in a pair of quality outings in his last two starts, allowing a combined one earned run in 11 innings. In fact, Houser has now given up only 19.2 innings. That's the kind of rhythm that you want to target on the waiver wire.
If we break down his numbers into only this stretch, we see a slight improvement in strikeout rate (18.7%) with decent advanced metrics (3.89 SIERA).
While there still isn't much upside here in terms of strikeouts, at least he's getting a bit more than before, putting him firmly on the streamer radar, especially since he's rostered in only 2% of Yahoo leagues right now.
Looking at Houser's pitch mix, we see that he continues to lean on his sinker, throwing it 46.6% of the time. This explains the lack of strikeouts, since this is a pitch that is always designed to induce weak contact.
It has a 9.3% whiff rate on the season. What's interesting is that Houser has thrown his four-seamer more often (19.9%, up from 11.7%). It's been an effective pitch for him, inducing a .230 xwOBA.
Houser's main weapon is his changeup, which has a 35.0% whiff rate. He also has a curveball that has a 27.8% whiff rate. But he only throws that 7.3% and almost exclusively to lefties.
That means that when Houser faces a lineup that has a lot of lefties, he has more strikeout upside, since he'll get to feature his two best whiff pitches more often. We see that reflected in the splits, as he has a 17.8% strikeout rate against lefties and a 12.8% rate vs. righties.
To that end, we can view Houser as a viable streamer while he's in a rhythm, with more upside if it's against a lefty-heavy lineup. If you're in a deeper league, I'm cool with giving him a shot to see where this goes.
Walker Buehler, San Diego Padres
18% Rostered (Yahoo)
Walker Buehler has a 4.79 ERA and a 1.39 WHIP with a 20.1% strikeout rate and a 9.5% walk rate in 120.1 innings this season. While those numbers don't jump off the screen at all, it's worth noting that his strikeout rate is up 3.8%.
Plus, the advanced metrics indicate that he deserves a bit better, as highlighted by a 4.27 xERA.
Buehler has been on a nice roll lately as well. We just saw him give up two earned runs on two hits with two walks and four strikeouts in six innings against the Mets in his last outing.
Before that, Buehler shut down the Brewers, allowing one earned run on three hits in six innings. Playing for a red-hot Padres team will give him a chance to rack up wins down the stretch, making Buehler pretty enticing, especially since he's only rostered in 18% of Yahoo leagues.
Looking at his pitch mix, Buehler has increased his cutter usage from 16.9% to 25.0%, which is a notable change. What's interesting is that this pitch has been much more effective for him this year, inducing a .294 xwOBA.
Last year, it was at a .421 xwOBA. While the pitch only has a 19.9% whiff rate, Buehler does have three weapons with a 27+% whiff rate, including his knuckle curve (27.2%), sweeper (27.8%), and changeup (28.3%).
Looking at Buehler's splits, we see that he has a 4.12 xFIP and a 20.5% strikeout rate against lefties, compared to a 4.41 xFIP and a 19.6% strikeout rate vs. righties.
This makes sense because Buehler throws both his changeup and knuckle curve much more often to righties. This gives him more weapons to rack up whiffs.
Up next is a matchup at home to the Twins, so Buehler will be in a good spot to rack up another quality start with a potential win.
The Padres are one of the hottest teams in baseball, making Buehler the most desirable pickup on this list, since the other two pitchers are playing for tanking teams. Pick him up to see if he can keep it rolling.
Jacob Lopez, Athletics
21% Rostered (Yahoo)
Jacob Lopez is putting up a 5.22 ERA and a 1.53 WHIP with a 20.5% strikeout rate and an 11.6% walk rate in 88 innings.
However, the underlying metrics indicate that Lopez deserves much better results, as highlighted by a 3.41 xERA. We're starting to see some positive regression with Lopez, especially in his last few starts.
Lopez has given up two earned runs or fewer in seven straight starts. During this stretch, he has a 2.36 ERA (2.47 xERA) and a 1.05 WHIP with a 28.1% strikeout rate and an 8.6% walk rate.
Those are impressive numbers, especially since they're backed up by the advanced metrics. This makes Lopez quite an intriguing add off the waiver wire.
Looking at Lopez's pitch mix, we see a four-seamer that has been quite effective this season, allowing a .267 xwOBA. He throws this pitch 34.1% of the time, so it's one of his main weapons.
Beyond that, Lopez has a slider that he throws 33.0% of the time. It's a pitch that allows a .242 xwOBA with a 29.1% whiff rate. This is his main weapon to rack up strikeouts.
Aside from those pitches, Lopez also throws a cutter 20.4% of the time, allowing a .320 xwOBA with a 25.3% whiff rate. This is a similar pitch mix to what he threw last year, so there aren't any notable changes. It's just worth mentioning how effective his four-seamer and slider have been this season.
Obviously, there are two main factors working against Lopez right now. For one, he has to pitch his home games at Sutter Health Park, which is one of the most hitter-friendly environments in MLB.
That's going to make it tough to avoid a blowup start or two down the stretch. On top of that, playing for a tanking Athletics team is going to make it difficult to rack up wins.
However, as we can see with Lopez's recent stretch, he can be an effective pitcher when he's on his game. While he's more widely rostered in Yahoo leagues, you can still get him in almost 80% of leagues right now.
I'd make the move considering how well he's pitching lately. The good news is that his next matchup will be on the road, even though it's a bit of a tough matchup vs. the Astros.
With that in mind, I recommend giving Lopez a look while he's firing on all cylinders, as he is right now.
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