Sneaky Fantasy Baseball Waiver Wire Pickups, Buys: Week 8 - Hot Pitchers To Sustain Success?

May 19, 2026

Andy looks at four sneaky fantasy baseball waiver wire pickups for starting pitchers in Week 8 (2026) on hot streaks, and sees if they can sustain their success.

Welcome, RotoBallers, to another edition of our hot-starting pitchers column. As always, we'll spotlight four starting pitcher shows that have begun to enjoy some recent success and determine if they are worth the waiver wire pick up or just fool's gold.

This week, we will take a look at the former top prospect who recently returned to the major leagues and a pitcher from the Mets who has had enough success in a "bulk" role after a rough start to the season.

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Cade Cavalli, Washington Nationals

15% Rostered (Yahoo)

Washington's No. 1 pitcher, Cade Cavalli, has been featured several times in this column. However, the young right-hander is putting together some of his most consistent baseball of the young season and is worth taking another look at as he could be stored for a productive June.

Over his first four games of the season (15 2/3 innings), the right-hander was far from effective, posting a hefty 4.60 ERA with a rough 1.72 WHIP. During this stretch, Cavalli walked 6.9 BB/9 while striking out only 13 (7.5 K/9). As a result, many managers selected him with the final pick of their raft, likely sent him to the waiver wire.

However, since this rough start, the former 22nd overall pick has begun to slowly turn the corner and may finally be finding his footing. Over his last 31 innings, Cavalli has posted a much-improved 3.77 ERA with a modest 1.45 WHIP. However, a closer look shows that his strikeout rate has skyrocketed, posting an elite 11.3 K/9, and his command has greatly improved, as he has walked just six hitters during this noted stretch.

More importantly, Cavalli has allowed two runs or fewer in all but two of these and has struck out at least eight hitters three times and hit the double-digit strikeout mark in two games. Is this recent improvement something that Cavalli can build upon? Or has he just been receiving some good fortune on the bump?

As shown below, Cavalli has not made many major changes to his pitch mix from April to May. He has only slightly leaned on his sweeper more, and it has almost become his No. 2 pitch, while he has dropped his four-seamer usage from 35% to 29.8%.

While the sweeper does not boost their most dominant batted-ball metrics, it has been very effective in driving up his strikeout totals. Per Baseball Savant, his sweeper (in May) has generated a hefty .388 xwOBA but has posted a stellar 31.8% whiff rate. His "No. 2" pitch, his knuckle curve, has been just as effective in the shift department, generating a high 38.2% clip while boasting a strong .244 xwOBA.

Even though Cavalli has greatly improved his command, which has significantly raised his floor in fantasy, he will need to develop a stronger fastball to find more sustained success. His four-seamer has generated a high .474 xwOBA in May and a similar .357 xwOBA in April, which has been the reason for much of his struggles.

This pitch has yet to post a whiff rate above 20.0% in any month. Per StatCast, Cavalli sits in the fifth percentile in fastball run value (-6), which places him among the worst qualified pitchers in the game.

Overall, he carries a 4.12 xERA with a .249 xBA, both of which sit just below the average marks. His 24.1% K% should continue to climb with increased usage of his sweeper, but his overall fantasy profile seems difficult to trust on a per-week basis.

For now, Cavalli remains an intriguing streamer in all 12-team leagues but should not be looked at as a set-it-and-forget SP4/SP5. He is taking the necessary strides, but still has ample work to do to enter the must-roster territory.

Cade Cavalli's 2Ks in the 3rd...and Sword. ⚔️ pic.twitter.com/brbNC5xt9F

— Rob Friedman (@PitchingNinja) May 16, 2026

Zebby Matthews, Minnesota Twins

10% Rostered

The next pitcher is the most interesting of this week's column. Zebby Matthews has shown high-end upside at Triple-A but has yet to put it all together in the big leagues. However, the right-hander was given a spot-start last week and did not disappoint, which earned him another start this week and potentially a permanent role going forward.

On May 14, Matthews faced the Marlins and tossed five shutout frames with only four hits and one walk allowed. He struck out seven. Given that Matthews posted a hefty 5.99 ERA over a career-high 79 1/3 innings in the big leagues last season, this outing came as a surprise to many.

Compared to last summer, Matthews made some notable tweaks to his pitch mix that are worth a closer look. In this one outing, Matthews deployed his high four-seamer 48.2% of the time, coming closer to the 41.1% usage rate it held last season. However, usage changes greatly in the secondaries.

As depicted in the visual below, Matthews raised his curveball and changeup usage and opted to drop his slider and cutter instead.

While the sample is small, this change could be what Matthews needed to succeed against giant MLB hitters. In this outing, his curveball was dominant, posting a 50.0% whiff rate with a minuscule .068 xwOBA. While his changeup was not overly impressive (.404 xwOBA), this change lowered his four-seamer to find more success as it carried a .239 xwOBA, compared to the .394 xwOBA it posted in 2025.

Even though his slider fell down to his No. 4 pitch in this game (it was his No. 2 last season), it still generated a high total of whiffs, posting a 28.6% whiff rate with a low .110 xwOBA.

Another component of Matthews' profile that is conducive for fantasy managers is his elite command. Throughout his time in the minor leagues and brief tastes of the majors, his walk rate also remained among the sport's best. In 2025, Matthews walked just 6.8% of the batters he faced (71st percentile), and over his 97 innings in the minors in 2024, he walked just seven total hitters.

Even though he disappointed managers in his first "full" taste of the majors last season, Matthews has many intriguing aspects of his profile that make him worth adding. There are not many pitchers who can emerge as an immediate WHIP specialist with high-end strikeout potential off the waiver wire.

David Peterson, New York Mets

10% Rostered

The 30-year-old southpaw has enjoyed strong stretches of relevance but has rarely been a must-stat option for an entire season. He put forth his best campaign in 2024, posting a low 2.90 ERA over 121 innings but showing limited strikeout potential, totaling just 101 and carrying shaky command, with a modest 1.29 WHIP.

In 2025, Peterson made a career-high 30 starts for the Mets and took a somewhat significant step back, holding a 4.20 ERA with a 1.37 WHIP. During these 168 2/3 innings, the lefty tallied 150 punchouts while maintaining the 9.0% walk rate he held the year prior.

As a result, entering 2026, Peterson was viewed as a reliable late-round volume option at the position but was not targeted for upside. Those who selected Peterson endured a tough blow to their early-season ratios as he posted a high 6.53 ERA with a 1.71 WHIP over his first 30 1/3 innings. In these seven starts, Peterson managed to tally 29 punchouts but had rough command of his pitches, walking 4.2 hitters per nine innings.

Following this rough skid, the Mets opted to shift Peterson to a long-relief role, which sent him to the wire in nearly all formats. However, this slight change in role has helped the left-hander regain his footing, which has surprisingly put him back on the fantasy radar.

Since moving to the bullpen at the start of May, Peterson has logged 13 innings (three games) and held a much-improved 2.77 ERA with a 1.23 WHIP. He has tallied 17 punchouts while showing elite command, walking only three hitters.

During this change in role, the left-hander has made a prominent tweak to his pitch mix. After relying on his slider as his No. 4 pitch in April, his slider has since moved to his No. 1, which drops his sinker to his No. 2 slot.

As shown in the results, his slider is looking quite useful as a true No. 1 pitch. This month, this pitch has generated a strong .236 xwOBA with a solid 25.7% whiff rate. His sinker remains a weakness (.394 xwOBA), but given that it has moved down his pecking order, he is able to limit the damage.

One pitch to monitor in his profile is his curveball. Deployed at a low 11.4% usage rate this month, it has generated a massive 60.0% whiff rate. In April, in a similar usage mark, it posted a stellar 37.0% whiff rate. If Peterson can continue to lean on his pitch, he can continue to average near a strikeout per inning, which would add another element to his fantasy profile.

While his long relief role does slightly hinder his ceiling, he is finding far more success in shorter four-inning outings. This role change does make him tougher to trust in standard leagues, but he is making the necessary adjustments to find steadier success. For now, he is a fine addition in 12+ team leagues and should be viewed as a high-end "streamer" when scheduled to see the bulk work against a weak lineup.

Anthony Kay, Chicago White Sox

15% Rostered

The final pitcher we will discuss enjoyed a hot start to the season but hit a kink in late April, which likely sent him to the waiver wire in most leagues. However, he has recently rebounded and could be worth a second look.

After spending two seasons overseas, Anthony Kay inked a deal with the White Sox and has since held a permanent role in their starting rotation throughout the first quarter of the 2026 season. Over the first 17 1/3 innings (four starts), Kay held his own in his first taste of big league action in two calendars, posting a 2.60 ERA with a 1.27 WHIP.

However, over his next two starts, Kay would surrender 12 runs in just 7 2/3 innings, which greatly inflated his ratios. Fortunately, it did not take long for the 31-year-old to bounce back.

Since May 1 (his last three games), Kay has posted a solid 2.25 ERA with a 1.31 WHIP. During this stint, he surrendered just four total runs and struck out 14 hitters while walking five. While his overall 15.3% K% does not scream upside, his ratios suggest he is getting the job done when you remove his two outlier performances.

Kay relies on a wide pitch mix to keep hitters off balance because of his lower velocity. As of writing, Kay has deployed at least five pitches more than 15.0% of the time, with his four-seamer leading the way with a 27.1% usage rate. Even though his four-seamer still ranks at the top of his usage rates, he began relying less on it in May, which is something to monitor.

As shown below, Kay has instead become a sinker-heavy pitcher and has drastically cut his four-seamer from his game plan.

Given that his four-seamer generated a .484 xwOBA in April, relying on it less in May makes sense from a results standpoint. However, his sinker has not fared much better, carrying a .325 xwOBA in May with a modest .407 xSLG. The lone pitch that has been effective is his sweeper, which has currently been his most-used in May.

Through these outings, this pitch has posted a high .429 wOBA on the surface, but holds a .297 xwOBA under the hood with a strong 35.0% whiff rate.

Overall, Kay enters Week 8 carrying a sixth percentile xERA and a ninth percentile xBA. His 6.32 xERA is more than two points higher than his 4.61 ERA on the surface, suggesting that even though he has begun to modify his pitch usage, he is still expected to take a massive step back. His low strikeout total and high 10.0% walk rate (36th percentile) also significantly lowers his ceiling and floor for fantasy.

While he has enjoyed a hot surge on the surface, Kay is a potential landmine that fantasy managers should avoid.

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