National League Rookie Roundup: 2024's Top Under-the-Radar Pitchers

With big-name first-year pitchers like Yoshinobu Yamamoto, Shōta Imanaga and Paul Skenes occupying the spotlight, you’re forgiven for not noticing these other less heralded arms putting together stellar rookie campaigns.
San Francisco Giants starting pitcher Kyle Harrison throws a pitch against the Pittsburgh Pirates.
San Francisco Giants starting pitcher Kyle Harrison throws a pitch against the Pittsburgh Pirates. / Darren Yamashita-USA TODAY Sports

Welcome to the Rookie Roundup, a weekly check-in on baseball’s best and most interesting first-year players. Last week, we highlighted a quintet of American League rookies who took winding paths to the big leagues and are making the most of their long-awaited opportunities in The Show. This week, we head over to the National League and give some shine to five under-the-radar pitchers who have been instrumental in their teams’ success.

As the calendar unofficially flips to summer, we’ve seen a select few dazzling rookie pitchers soak up most of the spotlight in the National League this season. Shōta Imanaga, Yoshinobu Yamamoto, Paul Skenes and Jared Jones have all rightfully received the bulk of the attention (and have all been praised in this space previously) for their sensational performances so far. But they’ve also overshadowed other rookie arms deserving of praise.

Below are five under-the-radar rookie pitchers who you might not have taken much notice of through the season’s first two months. We can expect more stellar play from Imanaga, Skenes and Co. throughout the rest of 2024, but this group shouldn’t be slept on.

All stats are updated through Monday’s games.

Ben Brown, Chicago Cubs

Brown didn’t break spring training on the Cubs’ Opening Day roster, but was quickly called up after Justin Steele injured his hamstring in the team’s first game of the season and landed on the injured list. He’s been used in a variety of roles so far, going back and forth between the rotation and the bullpen. Given Kyle Hendricks’s struggles and demotion to a relief role, we might be in store for more Brown starts for the foreseeable future, even if the 24-year-old’s long-term future could be better served in relief.

Listed at 6’6” and 210 pounds, Brown’s fastball sits at 96 mph, and he counters the heater with a knuckle curve that hitters so far have been baffled by, managing just a .138 batting average against with a whiff rate of 50.4%. If he’s going to stick in the rotation, he’ll need to develop a third pitch. But so far, he’s found success: after allowing six runs in 1 2/3 innings in his big-league debut, he’s posted a 1.91 ERA in 37 2/3 innings since.

Kyle Harrison, San Francisco Giants

After a seven-start stint last year, the 22-year-old Harrison has been a mainstay in the Giants’ rotation this season. He matriculated through the minor leagues relatively quickly after averaging more than 14 strikeouts per nine innings over 69 starts. Harrison’s been a steady presence for San Francisco, particularly this month: in five May outings, he’s 2–0 with a 3.67 ERA.

Walks have been more of an issue lately than they had been earlier in the season, though, as Harrison has issued 16 free passes compared to 24 strikeouts in May. He’s lasted just five innings in four of his last five starts, and he’ll need to sharpen his command to pitch deeper into games. Given the issues with the Giants’ other starters, though, Harrison has been a much-needed salve for an otherwise disappointing group.

Milwaukee Brewers pitcher Bryan Hudson
Hudson throws a pitch against the San Diego Padres in the sixth inning at American Family Field. / Benny Sieu-USA TODAY Sports

Bryan Hudson, Milwaukee Brewers

After being selected in the third round of the 2015 draft, Hudson spent eight years in the Cubs’ system, beginning his career as a starter before eventually shifting to the bullpen. He signed a minor league deal with the Los Angeles Dodgers in December 2022 and made a brief, forgettable big-league debut in ‘23, posting a 7.27 ERA over six appearances. Los Angeles ultimately designated him for assignment before trading him to Milwaukee in January.

All of this makes it that much more surprising that Hudson has quickly developed into one of the league’s most dominant relief pitchers. The 27-year-old has been a savior for a Brewers bullpen that’s seen a revolving door at closer in All-Star Devin Williams’s absence (though Trevor Megill has seemed to stabilize things of late). In 20 games, Hudson has amassed 30 1/3 innings with 36 strikeouts and just two runs allowed. At a towering 6’8”, the lefthander does not blow away hitters with velocity (his fastball averages just 91.8 mph), though opposing hitters have batted a combined .089 against his sweeper and cutter.

Mitchell Parker, Washington Nationals

Washington has followed up its World Series championship in 2019 with four straight losing seasons. It might be headed for a fifth in ‘24, though the Nationals have shown more fight than was widely expected out of them. And promising youngsters like Parker are a big reason why.

Parker was a fifth-round pick out of junior college by the Nationals in 2020, and by ‘23 had progressed to Triple A. He made a big impression in his major league debut on April 15, allowing just two runs in five innings at Dodger Stadium and picking up the win. In that game, he held the feared troika of Mookie Betts, Shohei Ohtani and Freddie Freeman to a combined 3-for-12 (he even struck Betts out twice and Ohtani once). The lefty has allowed three runs or fewer in all eight of his starts, with 38 strikeouts and just eight walks.

Matt Waldron, San Diego Padres

After a successful four-year college career at Nebraska, Waldron was drafted by Cleveland in 2019 and signed for a mere $5,000 bonus. He was traded to San Diego in ‘20 and made his major league debut last season. In between, he started throwing a knuckleball, something he’d tinkered with for fun going back to his Little League days but didn’t begin using professionally until ‘21.

What was once a fun side project is now a trusted weapon. Waldron’s knuckleball is his most-used pitch, with the righthander throwing it 35.7% of the time. Hitters have a .218 expected batting average against it and a 28.7% whiff rate. Over his last three starts, Waldron has found his groove, striking out 23 batters with a 2.81 ERA over 16 innings. It’s been a long time since a big-league pitcher routinely used a knuckleball, but Waldron is quickly bringing the pitch back in style.

Nick Selbe


Nick Selbe is a programming editor who also provides MLB and college sports coverage for Sports Illustrated. Nick, who has written about the MLB postseason and All-Star Game for SI, previously worked for MLB Advanced Media, Yahoo Sports and Bleacher Report. He graduated from USC in 2014.