How Rookie Starting Pitchers Are Performing So Far This MLB Season
Image credit: Jared Jones (Photo by Lachlan Cunningham/Getty Images)
We’re a month into the 2024 Major League Baseball season, and it’s time to start looking at how this year’s rookie starting pitcher class is performing.
We’re dealing with small samples, so the goal isn’t to jump to conclusions about these young arms. Pitchers are always tweaking things, and rookies, in particular, are known for undergoing drastic skill changes. Consider the improvements Grayson Rodriguez made in the second half of last season, for instance.
Below, we’ll start with a top-down view of the 2024 rookie starting pitchers class (min. 10 IP). From there, we’ll dive deeper into a few of the most interesting names.
Jared Jones, RHP, Pirates
It’s impossible not to start with Jones. He hasn’t just been one of the best first-year players. He’s been one of the most impressive pitchers in baseball, period.
Through six starts, Jones has a 37.5% whiff rate. For comparison, Spencer Strider had a 38.6% mark last year, a full-season record during the Statcast era (since 2015).
Jones easily leads rookie starters in swinging strike rate and K-BB%, and he ranks in the top two among all major league starting pitchers in those stats. Furthering the Strider comparison, Jones’ 18.9 SwStr% is identical to Strider’s from 2023, an all-time record dating back to when the stat was first recorded in 2002.
As evidenced by Jones’ 27.7 ball%, he’s quite comfortable living in the strike zone. It helps when you lead major league arms (not just rookies) in Stuff+. Jones’ strategy is essentially, “Here’s my best pitches, try and hit them.” It works the majority of the time, but one concern with his outlook moving forward is how much hard contact he’s allowing, especially in the air.
Among all qualified starters, only one starting pitcher allows as much overall hard contact while allowing as many fly balls—Dane Dunning.
When filtering specifically for fly balls, here are the league leaders for hard-hit rate allowed:
- Dane Dunning 63.3%
- Jared Jones 59.4%
A whopping 76.5% of all hard hits Jones allows have come on line drives and fly balls. Hitters are developing a clear strategy against him.
Batted ball data can be noisy this early in the year, but it feels as if we’ve already established how dominant Jones is from a swing-and-miss perspective. Based on how he’s been beaten so far, perhaps pitching out of the zone a little more often would be in his best interest moving forward.
Keaton Winn, RHP, Giants
Where Jones dominates with electric GIFs and highlights, Winn’s success is far more subdued.
As recently noted, Winn combines good stuff with strike-throwing ability and plenty of grounders. His 60.2 GB% not only leads rookies, but it ranks second in all of MLB, alongside some impressive teammates:
Winn’s fastball has some solid velocity, but Stuff+ doesn’t like its characteristics. Instead, Winn excels by primarily featuring his splitter. Winn uses it 42.3% of the time. According to Baseball Savant, only Reds reliever Fernando Cruz has a higher run value among all splitters.
The strikeout rate won’t blow you away, but a summer filled with pitching at spacious Oracle Park will only help Winn’s ratios. He’s quite underrated as the calendar flips to May.
Yoshinobu Yamamoto, RHP, Dodgers
There was slight concern about the $325 million man after he struggled in the Dodgers’ opening series against the Padres in Korea. That performance, in which Yamamoto allowed five earned runs in a single inning, still affects his season-long numbers. However, Yamamoto has been dominant since then.
Over his last five starts, the 25-year-old has a 35:5 K:BB to go along with a 2.00 ERA in 27 frames. This is backed up by his 2.59 FIP during the stretch and his 2.50 xFIP. This helps explain the difference in his season-long ERA (3.54) vs. SIERA (2.68).
Baseball America readers likely didn’t need a closer examination to know that Yamamoto is living up to the hype, but it’s nice to see his recent run of success is reinforced by the numbers.
Spencer Arrighetti, RHP, Astros
ERA minus SIERA isn’t everything, but at this point in the season, it’s a helpful calculation to try and get a sense of a pitcher’s “true talent.” Enter the Pasta Pirate, a delightful nickname Pitcher List’s Nick Pollack coined.
Arrighetti’s first MLB start was disastrous (7 ER in 3 IP), but the two most recent have been better (12:4 K:BB in 7.2 IP). Arrighetti has allowed a .500 BABIP this season and has a ridiculously low 52.8% left-on-base rate. It’s worth noting that good pitchers typically over-perform these metrics, while bad pitchers seem to under-perform them. Still, some positive regressions should be expected for Houston’s rookie hurler.
Arrighetti looked like someone to write off after his debut against the Royals, but he now has a strong 14.5% swinging strike rate through three starts. His 4.12 SIERA isn’t anything to write home about, but it’s better than some fellow first-year arms receiving more love than him. The ceiling remains limited, but Arrighetti is a nice example of the benefits of taking a holistic view of pitchers’ stats this early.
Gavin Stone, RHP, Dodgers
Sigh. There were reasons to be optimistic about Stone entering 2024, but we’re now up to 56 career innings with a 7.07 ERA, a 5.00 xFIP and a 5.7 K-BB%.
Stone’s average fastball velocity is up a tick from last season, and he isn’t getting hit as hard by the long ball. He’s been better overall, and that 12.3% swinging strike rate still pops compared to his fellow rookies. However, that SwStr% is down from 2023, and Stone wasn’t getting enough strikeouts then.
The changeup is fantastic, and he’s in the right team environment to keep improving, but we simply haven’t seen enough yet. Stone’s K-BB% trails Joe Boyle, Matt Waldron and José Soriano. He’s a “sell-low” candidate in dynasty leagues.
Luis Gil, RHP, Yankees
We’ll close with the No. 2 rookie starter by Eno Sarris’ Stuff+ metric. Similar to Jones, Gil is a favorite of the online baseball community. It’s easy to understand why:
The issue, as expected entering the season, is Gil’s control. Only James Paxton has a higher BB% than him thus far. A 40.2 ball% shows that regression isn’t imminent.
This lack of living in the zone would be a complete nonstarter for most, but Gil’s stuff is good enough that he’s surviving in the rotation. He has the sixth-lowest batting average allowed among pitchers with at least 20 innings this year.
Gil’s expected batting average, per Statcast, is in full-on reliever territory:
Still just 25 years old, Gil has enough upside that the Yankees will remain patient with his development. A high-walk starter isn’t normally one to recommend, but Gil’s upside is easy to dream on from a dynasty perspective. Additionally, he’s already displaying a floor of a low-end rotation arm or a high-end reliever.
