Slumping Starting Pitchers - Will They Turn It Around for Fantasy Baseball?

Ben Ueberroth looks under the hood for explanations as to why some of these prominent fantasy baseball arms have recently been underperforming.

As the baseball calendar rapidly approaches the mid-point of the season, fantasy managers can start to make heads or tails of "booms" and "busts" in the 2024 fantasy season. As with every season, surprise players have burst onto the scene to be top contributors. Others have continued to underperform relative to preseason expectations, leaving managers wanting more.

A more challenging situation to assess is a player who started the season hot only to hit a string of weeks with significantly worse performance. Are these players "hot starters" who are likely to stay relatively cold through the remainder of the year? Or is this a transient slump and managers can expect a return to form?

Ben Ueberroth (@UeberMD) takes a deep dive on a select group of arms who have been up and down in 2024. Evaluating those with reasons for optimism worth holding, while those on a downward trend could possibly still be moved for a player with a better rest-of-season outlook.

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Freddy Peralta, Milwaukee Brewers

After a 2022 season marred by a shoulder injury, Peralta returned to form in 2023, finishing the year with a top-75 ranking in standard category scoring. What has always popped about Peralta's stat lines are his strikeouts, amassing 210 strikeouts in 165.2 IP in 2023.

Through the myopic lens of strikeouts, Peralta has been a solid contributor in 2024 with a 31.0% K%, good for a top-10 ranking so far this season. So what is keeping Peralta from achieving the top-50 ranking that managers know and love? Currently, his ratios are higher than what one might expect for an "ace" with a 3.86 ERA and 1.12 WHIP. These both ballooned in June across three starts against the White Sox, Tigers, and Reds in which Peralta gave up 3 ER, 3 ER, and 6 ER, respectively.

Interestingly, Peralta's BABIP is what jumps off the page the most when first looking at his peripheral statistics. Currently sitting at .296, Peralta's BABIP in 2024 is significantly higher than his career mark of .271. In his stellar 2021 season, his BABIP sat at .230.

BABIP is often equated to "luck," and that can be a useful approximation in broad strokes analysis. But going a step further, hitters have been making better contact so far in 2024 against Peralta on the basis of 10.0% Barrel%, well above Peralta's career mark of 7.4%. Barrel% encompasses a combination of location on the barrel of the bat at the time of contact ("sweet spot") as well as launch angle. Peralta's GB% is also down to 37.6% in 2024 from 41.7% in 2023, another peripheral statistic suggesting "better" contact against Peralta in line with the Barrel% numbers.

Going one layer deeper, the concern seems to be with his slider. Peralta's slider heat map so far in 2024 shows significantly more pitches staying over the meat of the plate, which is not a desirable characteristic for a lateral-moving put away pitch. His curveball is suffering similar issues, spending much more time towards the top of the strike zone. His slider Whiff% is down to 38.4% in 2024 from 46.0% in 2023, and his curveball Whiff% is down to 24.0% in 2024 from 33.8% in 2023.

Peralta will continue to accrue strikeouts. The Brewers sit atop a weak NL Central and seem poised to provide a fair amount of Win opportunities for Peralta. Unfortunately, until his breaking balls come back to life, his ratio (and ace) upside may be limited in 2024 compared to 2023.

Brayan Bello, Boston Red Sox

Bello is underperforming relative to his preseason rankings by the largest margin of this list, and it is a wide margin. Projected in the top 200 for most ranking outlets, Bello had significant preseason hype as a solid SP3 with SP2 upside, particularly at the relatively young age of 25.

Unfortunately, an injury to his right latissimus dorsi muscle put Bello on the shelf for a couple of weeks, and since then, Bello has given up 2 ER or more in every start in May and June. But how much of this can be objectively pinned on his injury?

The first place to look for injury-related limitations is velocity. Bello's primary pitch (which could be called a fastball, sinker, or sinking fastball, depending on one's definition of these pitches) is averaging 95.7mph across all of 2024, even slightly higher than his 95mph average for this pitch in 2023. Since coming back from injury specifically, he continues to throw this pitch 95mph or higher consistently. The injury is not impacting his velocity.

Control is the next obvious concern, and this is where the numbers are a bit more divergent for pre-injury and post-injury Bello. Bello's BB% is up significantly in 2024, up to 8.6% from 6.7% in 2023. While 8.6% in and of itself is not terribly high, it can be a big difference maker for Bello in particular. He has always carried a high BABIP, with a .327 career number and a .303 BABIP in 2024. Hitters are able to put Bello's pitches in play in a way that leads to hits. A pitcher with a lower number that can limit damage with runners on base may not suffer as much from an inflated BB%, but Bello does. Perhaps some of this is pitching in Fenway Park, but it is not like that is a fixable problem for fantasy managers.

Brayan Bello had a solid start today, tossing 6.0 IP with 2 ER, 7 H, 6 K, 2 BB

Bello allowed a lot of base runners, but Toronto batters struggled to do damage against his sinker and changeup pic.twitter.com/WQypfF51wc

— Thomas Nestico (@TJStats) June 20, 2024

The setup for disaster with these extra baserunners is very real. Bello is giving up more walks leading to more damage. Lat injuries can linger. His 20.1% K% does little to salvage his blow-up potential. While he may have some strong outings, one has to wonder if the preseason hype was really deserved or if Bello was more of an SP4/5 than he ever was an SP2/3.

Triston McKenzie, Cleveland Guardians

Like Bello, McKenzie has been battling a serious injury for a pitcher in 2024. Unlike Bello, this injury was known in 2023 and was at least partially incorporated into 2024 expectations for McKenzie. McKenzie opted for rest and rehab over surgery (Tommy John surgery) for a partially torn UCL in 2023. While he has clearly been able to pitch at some level consistent with an MLB-caliber player, this is a remarkably concerning injury. The UCL is a key component of pitching in general and specifically generating velocity at the elbow.

Unfortunately, the impact of this injury is obvious. McKenzie's average fastball velocity is down to 90.9mph in 2024 from 92.4mph in 2023. With that, this pitch's Whiff% has plummeted to 10.3% in 2024 from 17.4% in 2023. In turn, his slider is suffering. That pitch was dominant in 2023, holding an eye-popping 57.3% Whiff% and 31.6% PutAway%. Both of these slider numbers are down significantly in 2024, with a 36.8% Whiff% and 20.8% PutAway%. One has to imagine that the closer average velocity of his fastball-slider combination is at least partly to blame for this, all derived from his injury.

His strikeout numbers have followed suit. In 2022 and years prior, McKenzie consistently held a K% above 25.0%. In 2024, he currently holds a 21.0% K%. In 2022, he also impressed with a 5.9% BB%, which has ballooned to 13.5% in 2024. Although the Guardians provide opportunities for their starters to accrue Wins, McKenzie is clearly pitching hurt and should be left as a streaming arm at best.

Ryan Pepiot, Tampa Bay Rays

Pepiot held a lot of promise and excitement coming into 2024. After coming up through a strong Dodgers farm system, Pepiot would finally get his shot as a full-time starter for what was supposed to be a strong Rays club. The Rays have certainly underperformed, and so has Pepiot.

Like Peralta up top, the bugaboo for Pepiot in 2024 has been his ratios. He continues to provide strikeouts at an above-average, if not elite level. His 27.8% K% is above his career average of 26.3%, backed by a vicious 95mph fastball that touts a 34.6% Whiff% and 23.0% PutAway%. He has become more well-rounded this year with the addition of a curveball and moving fastball (cutter), but his changeup remains his lethal off-speed pitch with a 28.2% Whiff% and 24.7% PutAway%. The stuff is there.

Ryan Pepiot's 4-Seam Fastball leads all starters with a 36.3 Whiff% pic.twitter.com/h3SP7vex48

— Thomas Nestico (@TJStats) June 11, 2024

With hard throwing comes hard hits. So far in 2024, Pepiot is sporting an ugly 41.4% HardHit% and 10.1% Barrel%. When hitters connect, it is a meaningful connection. However, Pepiot also has multiple ways that he mitigates damage. He holds a solid 17.1% CStr%, showcasing how he effectively locates his pitches in the zone. While he holds a pedestrian 8.5% BB%, coupling that with his K% leads to a 19.3% K-BB%, good for a top-30 ranking across the MLB in 2024. A .259 BABIP in 2024 against a .234 career BABIP suggests, if anything, balls in play are going for hits more often than Pepiot's historical "average".

The Rays need a global turnaround to provide more Win opportunities for Pepiot, but his under-the-hood numbers suggest a high-upside, strikeout-forward flamethrower. These stereotypes always inherently carry ratio risk to some degree, but Pepiot should see his ratios trend in the right direction over the coming months. Buy him low, hold him if you have him, and expect SP3 numbers, if not SP2, once 2024 is said and done.

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