Welcome to the Rookie Roundup, a weekly look-in on baseball’s best and most interesting first-year players. Last week, we looked at Jackson Holliday’s resurgence and the Orioles’ fresh crop of other young stars. Next up is a peek at the wide-open National League wild-card race, which could be decided by several rookies playing key roles for contending clubs.
Last year’s trio of National League wild-card teams produced the eventual pennant-winning Arizona Diamondbacks and the Miami Marlins, who fought their way into the postseason despite a minus-57 run differential. So we need only to look into the very recent past to realize that this is a race that, no matter how curious the final results may be, can send shockwaves throughout October.
At the time of this writing, nine NL teams are within five games of a wild-card spot with seven weeks of games left. Five of those clubs have at least 61 wins, and while none of the nine can be counted out quite yet, time is running out to make moves to the front of the pack.
In a race this tight, and with such little time remaining, the difference-makers will likely come from less obvious places. Each of the teams still in the hunt have relied upon contributions from its rookies to reach this point, and how that group of inexperienced players fares down the stretch could very well be the difference between who makes the postseason and who gets left out.
Here’s one rookie to watch for the top five wild-card contenders as we head for the home stretch.
Justin Martinez, RP, Arizona Diamondbacks
The Snakes stormed the Fall Classic last year thanks in large part to a lights-out bullpen that came out of nowhere following a regular season that produced middling results. This year’s group has similarly been a mixed bag, but a breakout from the 22-year-old Martinez has come at the perfect time.
Signed as an international free agent in 2018 when he was only 16, Martinez progressed through the minors and made a brief 10-game debut in ‘23. He opened this season in Triple A but was called up in mid-April and immediately thrived, allowing just one run through his first 25 innings. Since Paul Sewald was demoted from the closer’s role, Martinez has notched two of Arizona’s last four saves, with Ryan Thompson and A.J. Puk logging one each. The Diamondbacks will likely maintain a closer-by-committee setup, but Martinez has more than proved himself worthy of the role. Over 51 1/3 innings, he’s allowed just one home run with 62 strikeouts and a 64.5% ground ball rate, the highest among pitchers with at least 50 innings.
Yuki Matsui, RP, San Diego Padres
Jackson Merrill has gotten plenty of deserved shine in this space, and would be a Rookie of the Year frontrunner in any other non–Paul Skenes season. So in the interest of variety, we’ll go with Matsui, who’s played a key role as part of a fortified Padres bullpen that’s not short on high-leverage options.
Back-to-back shaky outings broke a run of dominance for the diminutive lefthander. From June 7 to Aug. 7, Matsui gave up just three runs with 30 strikeouts over 23 1/3 frames, regularly being trusted in high-leverage spots. The white-hot Padres have lots of options in the late innings with closer Robert Suárez, Jeremiah Estrada and Adrian Morejon, but Matsui has proven himself capable of being included on the menu of options to pitch in big spots.
Spencer Schwellenbach, SP, Atlanta Braves
As Atlanta has hit a skid that’s put its six-year playoff streak in jeopardy, the 24-year-old Schwellenbach has been one of the few bright spots. The Braves have had to dip into their pitching depth this season, with injuries striking at various points throughout 2024. And Schwellenbach, a second-round pick in ’21, has provided some much-needed stabilization for a thinned-out rotation.
In his last six starts since the beginning of July, Schwellenbach is 3–1 with a 2.54 ERA, striking out 45 hitters with just three walks over 39 innings. He’s logged at least six innings in all five outings after doing so just 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 playoff picture.
José Buttó, RP, New York Mets
Since June 3, the Mets’ 37–22 record is the third-best in the majors. And while there are many factors that have contributed to their turnaround, Buttó’s emergence as a trusted relief pitcher has been one of the most impactful.
The 26-year-old began the season in Triple A but was called up in April as part of New York’s starting rotation. He fared well in that role, posting a 3.08 ERA over seven starts, though a 38-to-21 strikeout-to-walk ratio propped the ERA on a shaky foundation. He was demoted back to the minors in May but returned on July 2—this time as a reliever, and the results have been outstanding.
Buttó has allowed two runs over 20 2/3 innings, striking out 24 compared to just six walks. Opposing batters have hit just .121 against him since his move to the bullpen. And he’s been trusted to pitch in high-leverage spots: In 10 relief appearances, he’s logged four wins, two holds and two saves.
Tyler Fitzgerald, SS, San Francisco Giants
Fitzgerald has been a godsend for a Giants team that’s won 12 of its last 16 games to surge right back into the thick of the playoff hunt. Through the first half of the season, Fitzgerald saw his name in the starting lineup just 21 times, posting a solid yet unspectacular .768 OPS over only 86 plate appearances. Since the All-Star break, the 26-year-old has hit his way into an everyday role.
Fitzgerald has started every day since July 20, a span of 22 games that’s seen him produce an eye-popping .349/.411/.791 slash line with 10 homers and five stolen bases. His 12 home runs on the season rank fourth among NL rookies, despite the trio ahead of him (Merrill, Chicago’s Michael Busch and Milwaukee’s Jackson Chourio) all logging more than double the amount of plate appearances as Fitzgerald.
Is that type of production sustainable? Well, no, particularly not when Fitzgerald’s strikeout rate is nearly 30% and his BABIP is approaching .400. But with an expected wOBA still looking strong at .353, there’s enough evidence in the consistent hard contact that Fitzgerald’s able to make to support him being a key contributor for the stretch run. And hey, if he’s able to maintain anything remotely close to what he’s done over the past few weeks, the Giants could be poised to break through the crowded field and get back to the postseason for the first time in three years.
This article was originally published on www.si.com as National League Rookie Roundup: Wild-Card Race Difference-Makers.
