Ranking the rookies in the MLB postseason by their potential impact

The 12 teams in the playoffs include a number of rookies who should play prominent roles in the postseason, from multiple Rookie of the Year contenders to a few recent callups who could step up to handle significant duties in a short series. Here's my quick ranking of the top rookies in the postseason based on how much of an impact I think they could have, given their likely playing time and usage:

Chourio just turned 20 in March, started the year as the Brewers' centerfielder, and made some adjustments in late May/early June to emerge as one of the best rookie hitters in baseball. From June 1, when he had his worst triple-slash line of the season, onward he hit .303/.358/.525, picking up offspeed stuff better and chasing less out of the zone so pitchers couldn't exploit him low and away or just on the outer third. He's also a plus defender in either outfield corner and could handle center if needed.

I've mentioned before that I think Merrill should be the NL Rookie of the Year, but I do think he has some flaws at the plate that might come up more in a short series against an opponent's best pitching. When he makes contact, it's pretty consistently hard contact, leading to a lot of red on his Baseball Savant page, including some expected stats (what kind of production you should expect given his quality and frequency of contact) in the top 5 percent in all of baseball.

One thing to watch for is how much he's willing to chase stuff out of the zone; he hit those pitches well during the regular season, but I'd anticipate that the typical pitches he sees out of the strike zone in October will be better than the typical ones he saw in the regular season. Another concern is that Merrill struggled badly against lefties this year, and while he's young enough to expect him to improve on that over time, the Padres may want to at least move him way down in the lineup if they face a lefty starter.

Yamamoto returned from a three-month IL stint to make four abbreviated starts in September, throwing 16 innings, striking out 21, walking five, allowing one homer and seven total runs. He averaged 95.5 mph on his four-seamer, right in line with where he sat before the injury, so while I doubt he works very deep into starts, he should remain effective in 4-5 inning stints. His splitter is a true out pitch that helped him to a reverse platoon split this year, although neither right- nor left-handed batters even managed a .300 OBP against him.

With Nestor Cortes on the shelf, Gil's role becomes even more important for the Yankees, and unfortunately Gil limped to the finish line this year after a strong first half. After the All-Star break, he walked 28 in 49 1/3 innings and posted a 4.20 ERA/5.21 FIP, even with extra time between starts several times in that span. He should get more than a full week of rest thanks to the Yankees' first-round bye, however, which may help him get back the little bit of velocity he lost in September. He relies more on his offspeed stuff than his four-seamer, however, so I'm less concerned about that last part than I might be for other pitchers.

The O's will have several rookies on their playoff roster, but only Cowser seems guaranteed a regular role. After a dismal first half, Cowser switched to a lighter bat right after the All-Star break and at least came into some more power, with 12 of his 24 homers and a .268/.337/.477 line in the second half (albeit with a 31.9 percent strikeout rate too). Cowser whacks fastballs from right-handers and generally hits the ball hard when he makes contact, but he whiffs over 40 percent of the time he swings at anything that's not a fastball and he has had trouble hitting left-handed pitching dating back to his time in the high minors.

Wells has shown he can hit right-handed pitching well, with all 13 of his homers against righties and a .236/.327/.434 line, improving as the season went along, although he remains a cipher against lefties and the Yankees should start Jose Trevino any time their opponents start a southpaw.

Schwellenbach has become one of Atlanta 's best starters in his rookie season, finishing in the top 5 among NL rookie pitchers in WAR thanks to a very strong four-pitch mix highlighted by a plus splitter and arguably a plus slider with huge vertical break. There's a caveat here, though — Schwellenbach threw on Monday in the first game of Atlanta's doubleheader against the Mets , so he's not likely to appear at all until the Division Series, if they get that far.

Ortiz, a natural shortstop, played elite defense at third base for the Brewers this year while producing league-average offense, enough that he almost matched the guy for whom he was traded, Corbin Burnes , in fWAR (3.1 vs 3.7). Ortiz is a high contact hitter who has some sneaky pop, and could easily slide over to short if needed.

By Statcast's metrics, Smith's four-seamer was the most valuable pitch in baseball in 2024, worth 28 runs above average, and he uses it a ton. It doesn't have elite movement, but he does have huge extension, 7.4 feet, so hitters have less time to react to it, and he sets it off with a decent splitter. Manager Stephen Vogt has been very uncreative with his relief usage, but Smith and Emmanuel Clase have been so effective that it hasn't mattered. One thing to note is that Smith hasn't faced more than five batters in an appearance in two months, and in the second half was largely a one-inning guy.

I'm including Meadows over fellow Tigers rookie Colt Keith because I think Meadows is more likely to have a significant impact on a single game or series thanks to his defense; he's now at +10 runs saved over his career in 976 centerfield innings, or about 15 runs per 162 games. He showed some improvement at the plate after an early-season demotion to Triple A, and while he's a fringy hitter overall, he has some pop and doesn't chase too much out of the zone.

Myers' year might have been the flukiest of anyone on the list, and I'm not sure I'd want him in the rotation for a short series, but the Brewers' other options all have warts as well. Myers doesn't throw hard and doesn't have a plus pitch, succeeding with excellent control and a huge dose of luck — he allowed just a .282 BABIP this year (helped by the Brewers' strong defense) and had an 81.1 percent strand rate, neither of which is sustainable over the long term.

Kerkering's got a great sinker/slider combo and can lay waste to righties with either pitch, but allowed a .347 OBP to lefties and doesn't have another pitch to attack them with. He's still effective and useful in the right spots, but he should be behind several other relievers on the call list, based on who's coming up for the other side.

At the time I'm writing this, we don't know who's on any postseason rosters, so it's possible Jobe won't be on the Tigers' for the first round ... but Jobe would be an outstanding weapon for Detroit, whose bullpen threw 694 innings this year, 60 more than any other AL team. With a plus fastball/changeup combo, he should be good against left- and right-handed batters, and could even work multiple innings since he's spent almost the entire year as a starter (in fact, he probably should do that, rather than working short relief on back-to-back days).

Kevin Kiermaier dislocated the ring finger on his left hand over the weekend and is "day to day" right now; if he can't go, Pages is a potential recipient of the playing time, especially if the Dodgers are facing a left-handed pitcher. He can play all three outfield spots if need be, although he's best suited to a corner. He does make hard contact and whacked lefties for a .357/.396/.520 line in 107 PA in the majors this year, making him at least a useful platoon player in a short series, but his poor swing decisions so far this year aren't a great harbinger for how he'll fare against better pitching in October.

(Top photo illustration of Jackson Chourio (left): John Fisher / and Jackson Merrill: Denis Poroy / )