Sneaky Fantasy Baseball Waiver Wire Pickups, Buys: Week 9 - Hot Pitchers To Sustain Success?

May 29, 2026

Andy looks at four sneaky fantasy baseball waiver wire pickups for starting pitchers in Week 9 (2026) on hot streaks, and sees if they can sustain their success.

Welcome, RotoBallers, to another edition of our weekly starting pitcher waiver wire column. As we have in weeks past, we will spotlight some potential breakout pitchers and determine if they can sustain their current hot success.

This week, we will look at a top post-hype breakout pick in Los Angeles and a few under-the-radar veteran pitchers who could hold solid streaming upside throughout the summer.

Be sure to follow RotoBallerMLB on X for all of our league-winning content and me, @A_Smith_FS, for any questions! Additionally, be sure to use code SMITH at checkout for 30% off on all premium packages. Let's dive in! Note - All advanced statistics referenced are updated as of Monday, May 25.

Roki Sasaki, Los Angeles Dodgers

35% Rostered (Yahoo)

Despite not pitching in a single MLB contest ahead of the 2025 season, Sasaki was being selected highly on draft boards given his overseas success. Ahead of the 2025 season, he inked a contract with the then-reigning World Series Champions and was primed to serve as a full-time starter in the rotation.

However, his first season in the major leagues did not go as planned, as the young right-hander stumbled and missed ample time due to injuries. He logged only 36 1/3 innings of action (eight starts in 10 appearances) and posted a high 4.46 ERA with a 1.43 WHIP. During this stint, Sasaki struck out just 28 hitters, which was a far cry from the 129 hitters he struck out in just 111 innings during the 2024 season in the NPB.

Sasaki would spend most of his summer on the shelf due to a right shoulder impingement. When he did return for their late-season playoff push, Sasaki would operate solely out of the bullpen but would begin to show some of his promised upside.

Entering 2026, Sasaki's fantasy value was at an all-time low and was likely selected with one of your final picks, given that a spot in the rotation was not even guaranteed. However, with Blake Snell opening the season on the injured list, Sasaki had a path to find his footing.

In April, the right-hander looked like his 2025 self, logging 22 2/3 innings (five starts) and posting a hefty 6.35 ERA with a 1.81 WHIP. During this stretch, Sasaki struck out just 22 hitters while walking a rather high 13. However, since May 1, Sasaki has been slowly turning the corner and looks far more comfortable in the majors.

Since May 1 (four starts), Sasaki has logged 23 frames with a much-improved 3.52 ERA and a 1.04 WHIP. The most notable improvement during this stretch has been his command, as he has only walked five hitters while striking out 21. Additionally, since allowing three runs in each of his first two starts this month, he has since surrendered just three total runs over his last 12 frames.

Is this recent surge the start of a post-hype breakout season?

Despite it being only one turn of the calendar, Sasaki's pitch mix looks nearly entirely different. May 1, which has helped him enjoy this surge in production. As shown below, the 24-year-old has continued to lean on his four-seamer as his No. 1 pitch but has instead opted to use a new split-finger as his No. 1 option, and has decreased the usage of his slider and forkball.

In April, he deployed his split-finger just 10.9% of the time, and it was very effective, generating a .225 xwOBA. However, in May, he has thrown this pitch 27.9% of the time, and it has remained elite, producing whiffs at an eye-catching 33.9% rate with a strong .227 wOBA. While it carried a higher .317 xwOBA under the hood, this pitch should remain effective, given the high total of swings-and-misses it generates.

By leaning on this pitch, his four-seamer has been far more effective as well. In the visual below, his four-seamers' xwOBA drops nearly 200 points, given this slight tweak in usage. The four-seamer plays much better with his split-finger operating as a true No. 2 pitch.

Even though Sasaki has dropped his slider usage by nearly seven points this month, the pitch has remained a strong No. 3 option and should remain prevalent in his repertoire. In May, this pitch had a 44.4% whiff rate and a .145 xwOBA.

While Sasaki's current 4.95 xERA (which places him in the 20th percentile) does not inspire much confidence among managers, he is taking the right steps forward, as shown by his pitch mix. If Sasaki cannot find success with this new split-finger and slider, his four-seamer will continue to generate promising results.

He enters Week 9 as a priority waiver wire target. We could be looking at a pitcher who has the upside to average more than a strikeout per inning with command that continues to improve each time he steps on the bump.

Stephen Kolek, Kansas City Royals

10% Rostered

The 29-year-old was a solid depth option in fantasy leagues last season after he tossed a season-high 116 2/3 innings to the tune of a 3.51 ERA and a 1.14 WHIP. However, his very limited strikeout upside (16.7% K%) did not attract many managers in the preseason, and he likely went underrated in early all formats.

Kolek actually opened the 2026 season in the minor leagues but returned to Kansas City at the start of May. Over his first two outings, Kolek endured some growing pains as he adjusted, surrendering eight runs over 10 2/3 innings with a modest 9:3 K:BB. However, since this rough start, Kolek has been nothing short of dominant.

In his last two outings (including a complete game shutout), Kolek has logged 15 1/3-straight shutout frames with eight hits, two walks, and five punchouts. On May 23, he shut down the Mariners, holding them to just four hits and one walk over these nine clean frames.

Given that he enjoyed some success last season, he is worth a closer look as we head into the remainder of Week 9.

Compared with his 2025 pitch usage, Kolek's pitch mix has not changed much. The only slight modification has been his slight bump in his changeup usage and drop in his slider usage. However, Kolek still throws at least four pitches more than 10.0% of the time and mixes in two other pitchers more than 9.0% of the time, making him a true kitchen-sink pitcher.

However, when diving into each pitch, managers can begin to spot warning signs in his profile. His No. 1 pitch, his four-seamer, has posted a strong .156 wOBA on the surface, but carries a looming .367 xwOBA under the hood. However, his sinker carries a strong .294 xwOBA compared to the surface xwOBA of .310.

While his four-seamer could be due to some regression, his secondary options have remained rather consistent, as his changeup has been a reliable option for whiffs (22.2% whiff rate) and his cutter has been excellent at generating weak contact, as evidenced by the .197 xwOBA.

Overall, even though Kolek's four-seamer could be due for a step back, his stronger secondary options have helped limit the damage. He enters Week 9 sitting in the 78th percentile in xERA (3.13) but just below the average marks with a .244 xBA. His elite 5.1% walk rate should keep his WHIP low, but his sixth-percentile K% makes him a less-than-desirable asset for fantasy.

As shown last week, Kolek will hold value in favorable matchups but could take a massive step back against more formidable opponents. For now, managers in deeper 12+ team leagues should view him as a viable streaming option, but should not consider him as a "lineup lock" SP4/SP5.

Luis Severino, Athletics

20% Rostered

Luis Severino has been a high-floor fantasy option for the past few seasons, especially when not pitching at home in Sacramento. During the 2025 season, Severino logged 162 2/3 innings with a 4.54 ERA and a 1.30 WHIP. However, when on the road, Severino looked far more comfortable, posting a 3.02 ERA with a dominant 1.07 WHIP, compared to the 6.01 ERA when pitching in the hitter's paradise.

As a result, Severino entered the 2026 season as a viable streaming option given the right matchup. Unfortunately, his 2026 season did not begin the way he would have hoped, as he posted a rough 6.20 ERA with a 1.70 WHIP over his first 24 2/3 innings. Since this rough start, Severino has quickly found his footing, logging 37 innings to the tune of a 2.92 ERA and a 1.27 WHIP.

In this noted strength, Severino even had a five-run, 10-hit effort against the San Francisco Giants, which greatly affected his ratios. In his most recent showing, Severino turned in his best outing of the season, striking out 10 hitters over seven innings of two-run ball, facing the Angels (on the road).

Can Severino continue this bounce-back and remain a strong fantasy asset when pitching away from home? When looking at his pitch-mix in relation to April to May, Severino has not made noticeable shifts, as shown below.

The "major" shift has occurred in his increased usage of his sinker. Oval, this pitch generated a high .397 xwOBA with a low 15.4% whiff rate. His other primary fastball, his four-seamer, has not fared much better, posting a .300 xwOBA.

Overall, Severino's 4.07 xERA suggests he has gotten unlucky at times this season, but his recent surge is not very sustainable. He sits just above the average K% at 24.2%, which slightly raises his ceiling relative to Kolek. However, our high 11.7% walk rate does open the door for more improvements, as he has seen in his performance this season.

Like Kolek, Severino has little "upside" compared to Sasaki. However, Severino continues to hold his own on the road (3.38 ERA), which makes him a viable pick-up in deep 12+ team leagues as an SP5/SP6.

Slade Cecconi, Cleveland Guardians

5% Rostered

Let's round out this week's column with a name for deeper leagues. Cecconi had a rough start to the season, carrying a 6.56 ERA with a 1.57 WHIP over his first 35 2/3 innings, which put him firmly off the fantasy radar in nearly all leagues. However, since this cold start, Cecconi has gradually begun to improve and enters Week 9 on a bit of a hot streak.

Since May 7 (his last four outings), Cecconi has posted a strong 2.91 ERA with a 1.34 WHIP. During this stretch, the right-hander has struck out just 19 hitters but has shown solid command, walking only 2.9 hitters per nine innings. Last season, Cecconi held a 4.30 ERA with a 1.19 WHIP, but he is beginning to show an even higher ceiling. Should fantasy managers in deeper leagues look to "buy in" to this recent improvement?

As shown below, Cecconi has made some major changes to his pitch mix since the start of May, which may have helped kick-start this recent stretch. He has begun to rely on his sinker as his No. 3 pitch, and drastically reduced the use of his curveball and sweeper.

Cecconi has been operating as a three-point pitcher, with all three of these pitches being fastballs. His four-seamer has led the pack in May, posting a 28.9% uage rate but has not been very successful, holding a .328 xwOBA. However, his No. 2 option, his cutter, has been generating a weak .262 xwOBA, with an 21.8% whiff rate, and should be used as his "primary" option.

His sinker has generated a 346 xwOBA and has not fared too well, despite the increased usage.

Given that Cecconi has turned to all three fastballs, he drastically reduced his curveball usage, with a low 10.9% rate in May. However, the pitch has remained his go-to whiff option, generating a 26.7% whiff rate with a .183 xwOBA. If Cecconi can continue to mix in this pitch more often in June, he could not only see his K% increase but also enjoy more sustained success.

His 4.70 xERA suggests, like Severino, that his early-season struggles were "unlucky," but his recent surge is not very sustainable. His high-end command should keep his WHIP relatively low despite his looking .269 xBA under the hood. Like Kolek and Severino, Cecconi does not have the best underlying marks, which pushes him into the streaming territory.

Among the two names in this week's column, Sasaki's recent string of success appears to be the most sustainable, and he should be the priority target. The other three are best left for 12+ team leagues as a starter with the potential to become a weekly SP4/SP5.

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