Welcome to the Rookie Roundup, a weekly look at the best and most interesting first-year players in baseball. Last week we looked at Jackson Holliday’s resurrection and the Orioles’ new young stars. Next up is a look at the wide-open wild-card race in the National League, which could be decided by several rookies playing key roles for rival clubs.
Last year’s trio of National League wild-card teams produced the eventual championship winners Arizona Diamondbacks and Miami Marlins, who battled their way into the postseason despite a minus-57 point differential. So we only have to look to recent history to see that no matter how odd the final scores, this race has the potential to send shockwaves throughout October.
At the time of this writing, nine NL teams are just five games away from a wild card spot, with seven weeks of games remaining. Five of those clubs have at least 61 wins, and while none of the nine clubs can be written off yet, we’re running out of time to get to the top of the pack.
In a race this close and with so little time left, the crucial players will likely come from less obvious places. Each of the teams still in the race has relied on the contributions of their rookies to get to this point, and how this group of inexperienced players fares down the stretch could very well be the difference between who makes the postseason and who doesn’t.
Here’s a newcomer to keep an eye on in the home stretch among the top five wildcard contenders.
The Snakes stormed the Fall Classic last year thanks in large part to a stellar bullpen that came out of nowhere after a mediocre regular season. This year’s group was similarly mixed, but the 22-year-old Martinez’s breakout came at just the right time.
Signed as an international free agent in 2018 at just 16 years old, Martinez came through the minors and made a brief 10-game debut in 2023. He began this season in Triple-A but was called up high in mid-April and immediately flourished, allowing just one run in his first 25 innings. Since Paul Sewald was demoted to the closer’s role, Martinez has earned two of Arizona’s last four saves, with Ryan Thompson and AJ Puk each recording one. The Diamondbacks will likely maintain a closer-by-committee setup, but Martinez has more than proven himself worthy of the role. In 51 1/3 innings, he has allowed just one home run with 62 strikeouts and a 64.5% groundball rate, the highest among pitchers with at least 50 innings.
Jackson Merrill has a lot from earned shine in that area and would be a favorite for Rookie of the Year in any other non-Paul Skenes season. So for the sake of variety, we’re going with Matsui, who has played a key role in a strengthened Padres bullpen that has no shortage of high-leverage options.
Two shaky performances in a row interrupted a streak of dominance for the small left-hander. From June 7 to August 7, Matsui allowed just three runs and had 30 strikeouts in 23 1/3 innings. He was regularly trusted in crucial situations. white-hot Padres have plenty of options in the late innings with closers Robert Suárez, Jeremiah Estrada and Adrian Morejon, but Matsui has proven he can be added to the list of options for pitching in important situations.
As Atlanta has spiraled into a slump that has put its six-year playoff streak in jeopardy, Schwellenbach, 24, has been one of the few bright spots. The Braves have had to reduce their pitching depth this season due to multiple injuries in 2024. And Schwellenbach, a second-round pick in 2021, has provided much-needed stabilization to a thinned rotation.
In his last six starts since early July, Schwellenbach is 3-1 with a 2.54 ERA and 45 strikeouts with just three walks in 39 innings. He has gone at least six innings in all five games after doing so only twice in his first six starts. With Charlie Morton struggling, Max Fried still shaking off some rust after missing most of July with a forearm injury, and Reynaldo López currently on the injured list, Schwellenbach will need to maintain his form to keep the Braves from slipping out of the playoffs.
Since June 3, the Mets’ 37-22 record is the third-best in the major leagues. And while there are many factors that contributed to their turnaround, Buttó’s emergence as a reliable relief pitcher has been one of the most influential.
The 26-year-old began the season in Triple A, but was called up to New York’s starting lineup in April. He did well in that role, posting a 3.08 ERA in seven starts, although a 38-to-21 strikeout-to-walk ratio put the ERA on shaky ground. He was demoted back to the minor leagues in May, but returned on July 2 – this time as a reliever, and the results were outstanding.
Buttó has allowed two runs and 24 strikeouts in 20 2/3 innings, compared to just six walks. Since moving to the bullpen, opposing batters have only a .121 batting average against him. And he has been trusted to pitch in crucial situations: In 10 relief appearances, he has recorded four wins, two holds and two saves.
Fitzgerald has been a godsend for the Giants, who have won 12 of their last 16 games to get back into the playoff race. Fitzgerald started just 21 times in the first half of the season and posted a solid but unspectacular .768 OPS in just 86 at-bats. Since the All-Star break, the 26-year-old has fought his way into an everyday role.
Fitzgerald has played every day as a starter since July 20, a 22-game span in which he has hit a blistering .349/.411/.791 with 10 home runs and five stolen bases. His 12 home runs this season are fourth-best among NL rookies, although the trio ahead of him (Merrill, Chicago’s Michael Busch and Milwaukee’s Jackson Chourio) all logged more than twice as many batting appearances as Fitzgerald.
Is that kind of performance sustainable? Well, no, especially not when Fitzgerald’s strikeout rate is nearing 30% and his BABIP is approaching .400. But with an expected wOBA of still strong .353, there’s enough evidence to suggest that Fitzgerald’s consistent hard contact is a key contributor heading into the final stretch. And hey, if he can keep up anything close to what he’s been doing over the past few weeks, the Giants could be on the verge of battling through the crowded field and making the postseason for the first time in three years.
