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Andy looks at four sneaky fantasy baseball waiver wire pickups for starting pitchers in Week 21 (2025) on hot streaks, and sees if they can sustain their success.
Happy Tuesday, RotoBallers! With another week of MLB action in the books, it's time to do another deep dive at some starting pitchers who are available on most waiver wires.
This week, we will look at a prospect who just made their long-awaited MLB debut and an improving arm in Kansas City, among others.
Who should fantasy managers be targeting this week? Let's dive in!
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Note - All statistics are updated as of Monday, August 18
Joey Wentz, Atlanta Braves
10% Rostered
Joey Wentz has carved out a role in the Atlanta rotation and has flashed moments of dominance. In his last two outings, the southpaw has logged 11 1/3 inings ot the tune of a 1.59 ERA and a 1.06 WHIP. During this stretch, Wentz has struck out seven hitters and allowed five walks.
During his first four starts of the season, Wentz held a dosest 3.54 ERA with a strong 0.98 WHIP across 20 1/3 innings. The 27-year-old spent his previous 26 appearances pitching out of the bullpen, where he logged 37 innings ot the tune of a 6.02 ERA and 1.70 WHIP. As a long reliever, Wentz showed less strikeout upside, tallying only 34 over this time and walking 21 hitters.
Is Wentz taking the next step as he transitions to the rotation?
Wentz is a three-pitch pitcher who leans heavily on his four-seamer and mixes in a cutter and a curveball. In August, his four-seamer (49.% used) posted an elite .286 wOBA on the surface. However, under the hood, it carried a .340 xwOBA, which suggests regression is coming. In addition, this pitch held a .323 SLG, which is nearly 100 points worse than the .426 xSLG under the hood.
His No. 2 pitch, his cutter, showed similar metrics as evidenced in the elite .265 xwOBA on the surface, but the hefty .385 xwOBA sits underneath.
While his two fastballs are due for a step back, his curveball should remain relatively elite. In August, this pitch has generated a strong 31.6% whiff rate with a remarkable .243 xwOBA and a .307 xSLG.
As shown below, his overall xwOBA for each pitch has increased in relation to July. Seeing his underlying metrics take a step back as he transitions to a full-time starter is not something fantasy managers want to see.
While there is no doubt, Wentz has been rather impressive lately, fantasy managers should not trust him going forward. While he could still find value as an astute option in favorable matchups, Wentz is best to leave on your waiver wire in all standard leagues for the time being.
Joey Wentz's 2Ks in the 3rd. pic.twitter.com/6SvDPNrGkA
— Rob Friedman (@PitchingNinja) July 30, 2025
Nolan McLean, New York Mets
20% Rostered
Nolan McLean made his MLB debut this weekend and looked quite strong enough to pick up the victory over the Mariners. In this outing, McLean tossed 5 1/3 shutout innings with two hits and an 8:4 K:BB. Given his strong debut, fantasy players should look to snag him off the wire.
Early in the season, McLean was flashing similar upside down at Triple-A. He opened the season at Double-A but needed only five starts to prove he was ready to join Syracuse. With the top level in the New York system, McLean posted an elite 2.78 ERA, 1.10 WHIP, and a 97:38 K:BB through 87 1/3 innings of work.
While in the minor leagues, FanGraphs credited his curveball as being in his top pitch. In his scouting report, they gave this pitch a 55 Grade with a 60 future score, suggesting it can develop into a dominant pitch. In his debut, his curveball was the driving force for his success.
The curveball was deployed as his No. 3 pitch (20.9% of the time) and generated an eye-catjing 45.5% whiff rate with a .164 xwOBA. His No. 1 pitch, his sweeper, showed some concern (.432 xwOBA), but his No. 2 pitch, his sinker, was just as dominant, carrying a .227 xwOBA.
With his dominant curveball and strong production at Triple-A this season, McLean is a must-add in all formats this week.
All eight of Nolan McLean's strikeouts in his big-league debut 💪 pic.twitter.com/KGF2BFxYIV
— SNY Mets (@SNY_Mets) August 16, 2025
Jason Alexander, Houston Astros
20% Rostered
Another pitcher who transitioned from the bullpen to the rotation this season has been Jason Alexander of the Astros. In August, Alexander has been deployed as a full-time starter and has quietly been one of the most dominant starters in the sport. Through three outings (18 innings), the right-hander has posted an elite 1.00 ERA with a 0.61 WHIP.
During these three starts, Alexander has struck out 15 hitters and walked only four. During July, he made three appearances (two starts) but was very ineffective, holding a 4.61 ERA and a 1.76 WHIP.
Is his recent string of performances in August for real, or has he gotten a bit lucky?
Alexander typically relies on four pitches but significantly emphasizes two of them, his sinker and changeup, which he has deployed 72.5% of the time this month. His sinker has carried a solid .295 wOBA on the surface with a .407 SLG. However, like Wentz, this pitch does not carry the best metrics under the hood.
In August, his sinker has generated a .516 xSLG and a high .364 xwOBA. As shown below, his sinker has consistently generated a higher xwOBA in each of the past three months.
However, while his sinker appears to be trending in the wrong direction, his changeup is the opposite. In August, his No. 2 pitch has generated an elite .215 xwOBA with a .120 xBA and a .240 xSLG. This pitch also generated a solid 40.0% whiff rate with a 25.6% put-away rate. In the graph below, his changeup has bounced back quite nicely in August and is merging as an elite No. 2 pitch.
Overall, the 32-year-old sits with a 23rd percentile K% and a 27th percentile BB%. However, he has struck out at least six hitters in three of his last four outings and only posted a low 2.4 BB/9 over this stretch. In addition, he is also generating groudballs at an elite 47.4% rate, which should continue to play well given his increasing strikeout production.
Alexander is taking the right strides and is a name to monitor closely. Given his eligibility as an "RP" in most platforms, Alexander is worth a look as he could provide decent value being deployed in an RP slot in favorable matchups in deeper leagues.
If he can continue to show higher strike potential upside, he could be worth a look in all standard formats in the near future.
Jason Alexander against the Orioles: 6 IP, 3 H, 2 ER, 0 BB, 6 K, 76 pitches, 49 strikes, 29 swings, 7 whiffs, 92.6 mph average exit velocity. His ERA as an Astro is 2.63. It's not a lie if you believe it.
— Chandler Rome (@Chandler_Rome) August 17, 2025
Ryan Bergert, Kansas City Royals
15% Rostered
The final pitcher we will look at is Ryan Bergert of the Kansas City Royals. Bergert was shipped to the Royals shortly before the deadline in a deal that sent catcher Freddy Fermin to San Diego.
With the Padres during the first half, Bergert made 11 appearances (seven starts) and held a solid 2.78 ERA and a 1.18 WHIP through his first 35 2/3 innings in the big leagues. During this stint, Bergert struck out 34 hitters but struggled to command his pitches, allowing 18 free passes.
However, in his first three starts in Kansas City, the right-hander appears to have taken the next step in his development. Through three starts, the 25-year-old has tossed 16 2/3 innings to the tune of a 2.70 ERA, 1.07 WHIP, and a stellar 17:5 K:BB.
Since going to Kansas City, Bergert has made a significant change in his arsenal, deploying his sweeper more often. In July, Bergert threw his pitch just 6.7% of the time. However, in August, Bergert has deployed this 22.7% of the time, which is nearly as much as his No. 2 pitch, his slider.
This has given him strong results, as this pitch has generated an elite 2.04 xwOBA. By throwing this more often, his sldier has also begun to find more success, generating a .268 xwOBA in August, which is much lower than the .315 xwOBA it generated in July.
However, his primary pitch, his four-seamer, remains quite underwhelming as it has generated .388 xwOBA in August, which is very similar to the .371 xwOBA it held last month.
While his 4.71 xERA under the hood suggests he should not be able to keep up with his current 2.75 ERA, seeing him rely on his sweeper more often could help him offset this expectation regression. In addition, he has consistently limited hard contact (69th percentile barrel rate) and has struck out at least 17 batters in each of his last two games.
Bergert is a solid starting pitcher to add to your rotation in all 12+ team formats.
Ryan Bergert since being traded to
the Royals 👀16.2 IP
2.70 ERA
12 H
15 K
3 BBOpposing hitters are hitting <.200 against all three of his primary pitches on the year
Bergert’s SL/CH have whiff rates of 31% and 34% respectively, with an outlier FB that averages just over 93… pic.twitter.com/Yhni9VrAve
— Owen Hurd (@Owen_FBB) August 18, 2025
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