Are You For Real? Surprising Fantasy Baseball Pitcher Starts From Kumar Rocker and Walker Buehler

Elliott Baas looks at starting pitchers who turned in surprising starts recently. These SPs could emerge as fantasy baseball waiver wire targets and sleepers for Week 25, or simply mirages.

Welcome back to the "Are You For Real?" series as we dive into Week 26 of the 2024 fantasy baseball season. This week we're looking at a new phenom in Texas in Kumar Rocker, and a former phenom on the comeback trail in LA in Walker Buehler.

For those who are not familiar, this is a weekly column where we take starting pitchers who had surprisingly good starts over the past week and put them under the microscope to determine whether they're legit or just smoke and mirrors.

Roster percentages are taken from Yahoo! and are accurate as of September 16.

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Kumar Rocker, Texas Rangers – 26% Rostered

2024 Stats (AAA): 10 IP, 1.80 ERA, 1.84 FIP, 48.6% K-BB%
9/12 vs. SEA: 4 IP, 3 H, 1 ER, 2 BB, 7 K

Rocker was fantastic during his MLB debut on Thursday, allowing just one run over four innings and striking out seven. Rocker also racked up a whopping 17 swinging strikes on just 74 pitches in this one, showcasing some big-time strikeout potential. Is Rocker the real deal, or is he too risky to roster?

Originally a first-round pick by the Mets back in 2021, Rocker did not sign over injury concerns and was selected by the Rangers a year later. The injury concerns came to fruition as Rocker required shoulder surgery in 2021 and Tommy John surgery in 2023, only recently returning. Rocker works with a five-pitch mix consisting of a slider, four-seam fastball, sinker, curveball, and changeup.

Rocker may have four pitches at his disposal, but he leaned heavily on two of them against Seattle, the slider and fastball. The slider was actually his most used pitch at a 45% usage rate. An 85 mph offering, Rocker’s slider is very up-and-down and is also big and loopy. Here are a few examples from this start.

Looks like a nasty pitch, and Mariners hitters certainly felt that way too. Rocker earned an incredible 13 of his 17 whiffs with his slider on Thursday, good for a 62% whiff rate. Rocker had an unreal 39.4% swinging strike rate and 53.8% chase rate with this pitch against Seattle. Obviously, those numbers aren’t sustainable, but they highlight how filthy Rocker was with his slider against Seattle.

The fact that Rocker was facing Seattle may have played a role in his dominant performance. The majors are a world away from the minors, but facing the Mariners is a soft landing spot for a first-time starter. Seattle has a 27.6% strikeout rate against right-handed pitching this season, the highest in the major leagues. They are also bottom-10 in wOBA, ISO, and AVG against righties. Seattle has struggled at the plate all season and perhaps Rocker took advantage.

Weak lineup or not, Rocker still impressed in his major league debut and has some impressive minor league numbers to back himself up. Rocker has a 2.70 ERA, 13.5 K/9, and 11.0 K:BB ratio across all levels of the minor leagues this season. He’s only thrown 36.2 innings, but he could not have been more dominant in them. We don’t have a big track record to trust him yet, but Rocker is doing everything right so far.

Rocker’s fastball was another point of emphasis for him in this start. He threw the pitch 41% of the time against Seattle. Averaging 96.7 mph on the gun, Rocker got as high as 97.6 with his heater.

He displayed average spin with the pitch at 2,186 RPM but had plus vertical and horizontal movement with the pitch. He mostly focused on keeping the pitch up in this start, and he did earn three whiffs with the pitch. Rocker has plus velocity and movement with his fastball, and it could be an effective offering at the major league level.

The four-seamer and slider both look strong, but what else does Rocker have to offer? His next most used pitch was his sinker, which he threw 11% of the time in this start. The sinker could end up being a strong pitch for him as well—he did have a -7-degree average launch angle against with it in this start—but when it comes to a complete arsenal we usually want two secondary pitches, and Rocker didn’t display one in this start. He did throw three changeups, but we’d probably want to see him use the pitch more often going forward. He could also introduce his curveball, which he didn’t use in this start at all.

Rocker looks like a raw talent on the mound with big strikeout upside. He was seriously carving batters up in the minors before his promotion, and he continued the trend in the majors. It’s unlikely that another big pitching prospect or high-upside candidate appears on waivers this season, meaning Rocker could be your last chance to make a meaningful addition to their fantasy rotation. He’s worth adding in all formats due to his upside, even if it’s just to keep him away from a rival.

Verdict:

Other than Paul Skenes, Rocker may be the most electric rookie pitcher to debut this year. He put up some utterly dominant numbers in the minor leagues and has flashed big strikeout upside with his slider. The slider looked filthy in this start and had Seattle on the ropes from the first inning.

Rocker’s potential is just too good to pass up, especially at this point in the season when it’s hard to make meaningful additions to one’s roster. Proceed with caution if you already have a strong pitching staff or are protecting ratios in a Roto league. Otherwise, I think Rocker is a must-add player. He lines up to make two more starts this season against Oakland and Toronto, and neither team scares me away.

Walker Buehler, Los Angeles Dodgers – 52% Rostered

2024 Stats (prior to this start): 59 IP, 5.95 ERA, 6.09 FIP, 10.2% K-BB%
9/15 @ ATL: 6 IP, 3 H, 2 R (1 ER), 5 BB, 5 K

Buehler had one of his best starts all season on Sunday, allowing just one earned run over six innings while notching his first quality start since May 31. Buehler lowered his ERA to an ugly 5.54 following this start and has a juicy matchup at home against Colorado next time out. Could Buehler be a late-season hero, or is this righty too volatile to roster?

Originally a first-round pick by the Dodgers back in 2015, Buehler was one of the biggest pitching prospects in baseball prior to his promotion, and at first he lived up to the hype. Between 2018-2021 Buehler had a 2.82 ERA and 3.16 FIP over 564 innings. He was an All-Star twice during that stretch and finished fourth in Cy Young voting in 2021.

Unfortunately, the Tommy John bug bit Buehler and he missed most of 2022 and all of 2023 recovering, and if his 2024 stats are any indication, Buehler still has plenty of work to do to get back to his previous level. Buehler has a deep arsenal, throwing seven different pitches including a four-seam fastball, cutter, knuckle curve, sinker, sweeper, changeup, and slider.

Variety is the spice of life, and it was Buehler’s spice of choice against Atlanta. He threw all seven pitches at least once in this start, relying most heavily on his sinker and cutter. The reliance on his sinker is something new for Buehler, as he’s used his four-seamer as his primary fastball for most of the season.

Perhaps this shift towards the sinker is a good thing for Buehler. Batters are hitting .264 against the sinker with a .283 SLG and .293 wOBA. Buehler has an impressive 82.7 mph average exit velocity with the pitch, along with a 2-degree average launch angle.

That means batters are mostly tapping weak groundballs against the pitch, a positive outcome indeed. This weak contact also leads to exceptional expected stats, with Buehler posting a .224 xBA, .264 xSLG, and .268 xwOBA with his sinker this season.

The numbers against his sinker look great, especially in comparison to his four-seamer. Opponents are pulverizing Buehler’s four-seam fastball for a .357 AVG, .743 SLG, and .486 wOBA. Is he throwing a softball out there?

Even worse, batters have a .368 xBA, .715 xSLG, and .482 xwOBA against the pitch, meaning Buehler has earned every bit of his bad outcomes. He’s also allowed a 93 mph average exit velocity and 16-degree average launch angle against with the pitch, meaning the average hit against it is a screaming line drive.

Buehler has lost some velocity over the years, going from a peak of 96.8 mph in 2020 to just 95.1 mph this year. That’s still above average, but Buehler has lost a ton of spin and movement with the pitch as well. His 2020 peak had a four-seam spin rate of 2,546 RPM, but this season he’s averaging just 2,276 RPM with the pitch.

He’s also lost about four inches of drop with the pitch compared to its peak. The bottom line is that Buehler’s fastball has lost something post-surgery and looks to be a no longer effective pitch. A pivot to his sinker might be necessary to save his career.

What about Buhler’s most famous pitch, the knuckle curve? Scouts raved about Buehler’s curveball and it came as advertised when he reached the majors. Buehler used to have a swinging strike rate between 14-20% with the pitch pre-injury but has just a 9.9% swinging strike rate with his curveball this season.

He’s lost a ton of spin with the pitch, going from 3,042 RPM in 2020 to 2,576 RPM this season. Maybe Buehler was a beneficiary of sticky stuff back then, which juiced his spin rate a bit, but the drop-off is severe. He’s lost about five inches of drop with the pitch as well, meaning it’s simply a less effective version of a previously dominant pitch.

His stuff looks diminished, but perhaps a reliance on his sinker could allow him to survive on the mound. Unfortunately, another issue plaguing Buehler has been his pitiful control. His 8.7% walk rate is over 2.0% higher than his career walk rate, and he issued a whopping five free passes in this start. Buehler was lucky to only allow two runs in this one. He has now issued at least one walk in 11 consecutive starts and has issued multiple walks in six of 14 starts this season.

Verdict:

The name value of Walker Buehler might grab some attention in fantasy circles, but make no mistake, this isn’t the Walker Buehler of 2018-2021. Rather than fighting for a Cy Young, this Buehler is fighting to keep his rotation spot. He had a nice outcome in this one, but he worked around eight baserunners and still allowed two runs (one earned). His sinker looks like a solid groundball pitch, but his four-seam fastball and knuckle curve are clearly diminished pitches.

Hopefully, Buehler can rediscover these pitches next season because it’s a little sad to see what’s happened to him. He reminds me a little bit of Steven Matz, who looked amazing when he first came up but had his body destroyed by injuries and sort of lost it. For now, Buehler should be avoided in most circumstances. That being said, Colorado has a .277 wOBA and 28.6% strikeout rate on the road, so you could consider streaming Buehler in his next start, though you’d have to be a little desperate to do so.

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