5 breakout pitcher candidates to watch in 2023

February 16th, 2023

Dylan Cease, Shane McClanahan, Kyle Wright and Nestor Cortes were among last season’s biggest breakout stars on the mound, and another crop of talented arms is set to take flight in 2023. Here are the breakout pitcher candidates you should be keeping an eye on heading into the upcoming season, as selected by five MLB.com writers.

Dustin May, Dodgers
Key stat: 97.6 mph avg. fastball (four-seamers and sinkers) velocity

May has appeared in parts of four seasons for the Dodgers, but he has just 143 2/3 innings under his belt due in part to the pandemic and a 15-month recovery from Tommy John surgery. His return from the procedure saw him post a 4.50 ERA and a 4.38 FIP over six starts last season. However, it’s hard to forget how dominant May looked for a brief spell to open the 2021 campaign.

The lanky right-hander notched a 2.74 ERA with a 37.6% strikeout rate and a 6.5% walk rate over his first five starts that year as his results finally started to match up with his electric stuff. His elbow injury robbed him of the chance to finish off what could have been a breakout season, but he’s only 25 and has all the potential in the world. After all, the list of pitchers who throw upper-90s sinkers that move like this and can unleash elite-spin breaking balls like this isn’t very long.

-- Thomas Harrigan

Jesús Luzardo, Marlins
Key stat: 3.03 ERA / 2.87 FIP over last 12 starts of 2022

It feels as if we have been waiting for Luzardo’s breakout forever, but the left-hander will pitch virtually the entire 2023 season at only 25 years old. A consensus top-15 prospect before the 2019 and 2020 seasons, Luzardo has dealt with injuries (some self-inflicted), the challenges of the pandemic-shortened 2020 season and some seriously uneven performance since arriving in the Majors. The 2021 campaign, split up by a trade from Oakland to Miami, was a mess (6.61 ERA).

Last season also had its bumps, including a forearm strain that kept Luzardo out of MLB action between May 10 and Aug. 1. But look past that, and there are signs that the Peru native is ready to take a big step forward. With improvements to his strikeout and walk rates and quality of contact allowed, Luzardo drastically improved his expected wOBA to .287 -- within a few points of Luis Castillo, Gerrit Cole, Alek Manoah, Framber Valdez and Kevin Gausman. It all came together after Luzardo returned to action in August and dealt like a top-20 pitcher over his final dozen outings.

With two big-time, swing-and-miss pitches in his curveball and changeup, and improved command of his four-seam fastball, Luzardo looks ready to establish himself in a Miami rotation that is going to be counted on to carry the team. Now he just needs to stay healthy for a full season and let it eat.

-- Andrew Simon

George Kirby, Mariners
Key stat: .284 xwOBA allowed

Julio Rodríguez’s sensational Rookie of the Year campaign overshadowed all other rookies, including his own Mariners teammate Kirby. While it’ll be tough to overtake the rightful hype surrounding the J-Rod Show, Kirby -- a 6-foot-4, 215-pound 25-year-old -- is poised to make a name for himself in 2023.

After reaching the Majors in early May, the right-hander put together a strong debut season with a 3.39 ERA, 1.21 WHIP and 133 strikeouts in 130 innings, despite a .331 BABIP that was ninth highest among pitchers to reach 100 frames. Known for his control and command as the 20th overall pick in the 2019 Draft, Kirby walked only 22 batters in 25 big league outings, a total inflated by seven free passes over his final three starts. Still, his 4.1% walk rate was sixth best (min. 100 IP), directly in between Kevin Gausman and Max Scherzer.

Kirby isn’t some finesse soft-tosser, though; his stuff has ticked up as a pro, with his four-seamer averaging 95.3 mph and generating an impressive 26.4% whiff rate with Seattle. He also throws six different pitches regularly, giving him a wide-ranging repertoire to attack batters. Add it all up and you have a pitcher whose .284 xwOBA was 20th best (min. 350 balls in play) – tied with Luis Castillo, Gerrit Cole, Alek Manoah and Framber Valdez. After not letting Kirby throw more than 100 pitches in any outing in 2022, expect the Mariners to loosen the reins en route to a breakout.

-- Jason Catania

Ryan Pepiot, Dodgers
Key stat: 24.1% in-zone whiff rate as SP

Pepiot is a wild-card pick because there might not be a spot open in the Dodgers' rotation right away. But based on the stuff the Dodgers' No. 6 prospect showed in his first big league action last year, we're betting the 25-year-old right-hander just needs a chance. First of all, Pepiot posted a 10.4 K/9 in the Majors to go along with his 11.2 K/9 at Triple-A. His fastball, even though it "only" sits at 94 mph, has a 2,400-plus rpm spin rate that gives it strong rise (two inches more than an average four-seamer), which helped Pepiot generate a high 28% swing-and-miss rate in 2022. His 87 mph changeup gets nearly 17 inches of horizontal movement to the arm side, 2.5 inches more than an average changeup. And he throws a tight slider, also around 87 mph with above-average horizontal break.

Then there's this: A good sign for how dominant a pitcher can be is how often he gets whiffs on pitches inside the strike zone, since those should be the most hittable. In his starts, Pepiot got whiffs on nearly a quarter of the swings against his in-zone pitches (24.1%), ranking among the top 10 starters in this smaller sample. That list, for reference, was topped by Jacob deGrom, Shane McClanahan and Spencer Strider. Further indication of how Pepiot commanded the zone: if you add in called strikes, he got a called strike or whiff on over half of the pitches he threw in the strike zone (50.6%) -- the highest rate in the Majors.

-- David Adler

Hunter Greene, Reds
Key stat: 30.9% strikeout rate

When your fastball has touched 104 mph and you have a devastating slider to go with it, it’s not a stretch to predict a breakout season. But since Greene, like any other rookie, went through some early growing pains last year -- still managing to finish with a 101 ERA+ and 1.21 WHIP, not to mention a 30.9% strikeout rate -- 2023 may be his breakout campaign.

As pointed out by my esteemed colleague, David Adler, Greene had an incredible run to close out the season in September and October, posting a 0.78 ERA with a K/9 rate of 14.5. Adler notes that Greene’s fastball got even better over that stretch, even after he set an MLB record in his second career start for most pitches thrown in a game in the pitch-tracking era with velocity of 100+ mph (39). The harder fastball, as well as more frequent elevation of the pitch over the final month or so of the season, made Greene nearly unhittable.

With the first-year jitters out of the way, and with what he showed late in 2022, Greene could be on the cusp of something truly special in 2023.

-- Manny Randhawa