Every MLB team has at least one promising building block for the future, and several of them have been on full display this postseason.

That includes New York Mets slugger Mark Vientos, who has gone from being a disappointing top prospect in 2023 to a breakout star in 2024. He has been a driving force for the Mets during their current playoff run.

Vientos exhausted his prospect status last year, but the NL Rookie of the Year race between Pittsburgh Pirates starter Paul Skenes and San Diego Padres outfielder Jackson Merrill was one of the best in years. It remains to be seen who will take home the hardware.

Here, we've taken a closer look at each team's best player who was under 25 years old during the 2024 season.

A player's in-season age at Baseball Reference is defined as how old they are on June 30 at midnight, which is the midpoint of the season, so that was our cutoff for players needing to be shy of their 25th birthday.

Arizona Diamondbacks: OF Corbin Carroll

Age: 23

Stats: 158 G, 107 OPS+, .231/.322/.428, 58 XBH (22 HR), 74 RBI, 35 SB, 3.4 WAR

Corbin Carroll was one of the best players in baseball during the 2023 season when he posted a 133 OPS+ with 30 doubles, 10 triples, 25 home runs, 76 RBI, 116 runs scored, 54 steals and 5.4 WAR en route to unanimous NL Rookie of the Year honors.

He got off to a slow start to the 2024 season, but he turned it on during the second half, posting a .919 OPS with 17 home runs and 42 RBI in 64 games while again looking like a franchise cornerstone.

Honorable Mentions: C Gabriel Moreno (24), SS Geraldo Perdomo (24), RP Justin Martinez (22)

Atlanta Braves: SP Spencer Schwellenbach

Age: 24

Stats: 21 GS, 8-7, 3.35 ERA, 1.04 WHIP, 23 BB, 127 K, 123.2 IP, 2.7 WAR

A season-ending injury to Spencer Strider created a revolving door at the back of the Atlanta Braves rotation, but rookie Spencer Schwellenbach shored up the back of the staff after he made his MLB debut on May 29.

Over his final 15 starts, he posted a 2.54 ERA, 0.96 WHIP and 95 strikeouts in 92 innings, logging 10 quality starts along the way. With the season on the line in Game 1 of a doubleheader against the Mets on Sept. 30, he tossed seven innings of four-hit, one-run ball.

Honorable Mentions: OF Michael Harris II (23)

Baltimore Orioles: SS Gunnar Henderson

Age: 23

Stats: 159 G, 159 OPS+, .281/.364/.529, 75 XBH (37 HR), 92 RBI, 21 SB, 9.1 WAR

Since the Orioles moved to Baltimore in 1954, only Cal Ripken Jr. in 1991 (11.5) and 1984 (10.0) posted a higher single-season WAR total than Gunnar Henderson did during the 2024 season.

The 2023 AL Rookie of the Year had a .956 OPS and 28 home runs at the All-Star break before cooling off a bit in the second half, so he still has further room for improvement if he can maintain that level of production over a full season.

Honorable Mentions: OF Colton Cowser (24), SP Grayson Rodriguez (24)

Boston Red Sox: SS/CF Ceddanne Rafaela

Age: 23

Stats: 152 G, 82 OPS+, .246/.274/.390, 43 XBH (15 HR), 75 RBI, 19 SB, 2.8 WAR

The Red Sox inked Ceddanne Rafaela to an eight-year, $50 million extension just a few days after Opening Day. While he still has work to do refining his offensive game, he was extremely valuable to the Red Sox in 2024 thanks to his defensive versatility and run-production skills at the bottom of the order.

He split his time evenly between shortstop (647.0 innings) and center field (631.1 innings), and his 75 RBI trailed only Jackson Merrill (90) and Jackson Chourio (79) among all rookies even though the bulk of his at-bats came out of the No. 9 spot in the lineup.

Honorable Mentions: 1B Triston Casas (24)

Chicago Cubs: OF Pete Crow-Armstrong

Age: 22

Stats: 123 G, 88 OPS+, .237/.286/.384, 29 XBH (10 HR), 47 RBI, 27 SB, 2.4 WAR

It took Pete Crow-Armstrong some time to find his footing offensively, but he offered enough value with his defense and speed that the Chicago Cubs gave him a long runway to figure things out, and he looked like a rising star down the stretch.

From Aug. 1 through the end of the season, Crow-Armstrong hit .284/.337/.466 with 16 extra-base hits and seven steals in 176 plate appearances. His defensive metrics in center field (12 DRS, 7.7 UZR/150) were elite, and he ranked in the 99th percentile in sprint speed.

Honorable Mentions: RP Porter Hodge (23)

Chicago White Sox: SP Jonathan Cannon

Age: 23

Stats: 21 GS, 5-10, 4.49 ERA, 1.33 WHIP, 40 BB, 91 K, 124.1 IP, 1.9 WAR

After starting the season at Triple-A, Jonathan Cannon earned a quick call-up to bolster the Chicago White Sox rotation, making his MLB debut on April 17 with five innings of three-hit, one-run ball against the Kansas City Royals.

The 6'6", 225-pound right-hander ended up finishing third on the team in innings pitched (124.1) and WAR (1.9). Over his final 15 starts, he completed at least six innings nine times while logging a 4.43 ERA in 85.1 innings.

Honorable Mentions: SP Drew Thorpe (23)

Cincinnati Reds: SS Elly De La Cruz

Age: 22

Stats: 160 G, 119 OPS+, .259/.339/.471, 71 XBH (25 HR), 76 RBI, 67 SB, 5.2 WAR

The Cincinnati Reds had two of the best under-25 players in baseball in shortstop Elly De La Cruz and right-hander Hunter Greene, both of whom took a significant step forward during the 2024 season.

De La Cruz became just the sixth player in MLB history with 70 extra-base hits and 60 steals in a season, joining Harry Stovey (1889), Jake Stenzel (1894), Ty Cobb (1911), Juan Samuel (1984) and Ronald Acuña Jr. (2023).

Honorable Mentions: SP Hunter Greene (24), SP Rhett Lowder (22)

Cleveland Guardians: SS Brayan Rocchio

Age: 23

Stats: 143 G, 76 OPS+, .206/.298/.316, 26 XBH (8 HR), 36 RBI, 10 SB, 1.8 WAR

Brayan Rocchio won an open competition with Gabriel Arias for Cleveland's starting shortstop job during spring training. While his offensive numbers don't jump off the page, he provided terrific defense at a premium position.

He started 121 of 162 games at shortstop for the AL Central division winners, and he provided elite defensive metrics (10 DRS, 9.1 UZR/150) on his way to being an AL Gold Glove finalist alongside Anthony Volpe and Bobby Witt Jr.

Honorable Mentions: C Bo Naylor (24), SP Gavin Williams (24), OF Jhonkensy Noel (22)

Colorado Rockies: SS Ezequiel Tovar

Age: 22

Stats: 157 G, 103 OPS+, .269/.295/.469, 75 XBH (26 HR), 78 RBI, 6 SB, 3.7 WAR

After a productive rookie season in 2023, shortstop Ezequiel Tovar looked the part of a franchise cornerstone this year, posting improved offensive numbers across the board while finishing tied for seventh in the majors with 75 extra-base hits.

His .295 on-base percentage and 200 strikeouts speak to the work he still needs to do developing his offensive game, but his combination of extra-base power and standout defense (9 DRS, 8.1 UZR/150) make him a building block and potential early extension candidate.

Honorable Mentions: RP Victor Vodnik (24)

Detroit Tigers: OF Riley Greene

Age: 23

Stats: 137 G, 133 OPS+, .262/.348/.479, 57 XBH (24 HR), 74 RBI, 4 SB, 5.4 WAR

The No. 5 overall pick in the 2019 draft and a top-tier prospect during his time in the minors, Riley Greene has steadily improved over his three seasons in the majors, culminating in his first All-Star selection in 2024.

He hit .294/.353/.521 in 133 plate appearances with runners in scoring position, and provided a young team on the rise with an offensive star to serve as the centerpiece of an evolving offense. He still has another year before he becomes eligible for arbitration, making him one of the best bargains in the sport.

Honorable Mentions: OF Parker Meadows (24), SP Reese Olson (24), OF Wenceel Pérez (24), SS Trey Sweeney (24), 1B Spencer Torkelson (24), SP Keider Montero (23), 2B Colt Keith (22)

Houston Astros: SP Spencer Arrighetti

Age: 24

Stats: 28 GS, 7-13, 4.53 ERA, 1.41 WHIP, 65 BB, 171 K, 145.0 IP, 0.3 WAR

The No. 3 prospect in a thin Houston farm system at the start of the 2024 season, Spencer Arrighetti made his MLB debut on April 10 and provided some welcome support to an injury-plagued rotation.

He took his lumps early on, but hit his stride as the weather warmed up, posting a 2.68 ERA, 0.95 WHIP and 65 strikeouts in 50.1 innings during an eight-start stretch from mid-July through the end of August. His 171 strikeouts trailed only Chicago Cubs left-hander Shōta Imanaga (174) among all rookie pitchers.

Honorable Mentions: None

Kansas City Royals: SS Bobby Witt Jr.

Age: 24

Stats: 161 G, 171 OPS+, .332/.389/.588, 88 XBH (32 HR), 109 RBI, 31 SB, 9.4 WAR

Bobby Witt Jr. showed flashes of stardom as a rookie in 2022 and took a major step forward in 2023, but he broke through as a bona fide superstar this year while putting together a MVP-caliber performance.

He became the first shortstop in MLB history with multiple 30/30 seasons, led the AL in batting average (.332) and hits (211), and also made major strides defensively to earn a nod as a Gold Glove finalist. The 11-year, $288.8 million extension he signed in February is quickly shaping up to be a steal for the Royals.

Honorable Mentions: IF Maikel García (24), RP Angel Zerpa (24)

Los Angeles Angels: SS Zach Neto

Age: 23

Stats: 155 G, 113 OPS+, .249/.318/.443, 58 XBH (23 HR), 77 RBI, 30 SB, 5.1 WAR

The Los Angeles Angels pushed Zach Neto quickly through the farm system, as he made his MLB debut on April 15, 2023, less than a year after he was taken No. 13 overall in the 2022 draft out of Campbell University.

He tallied 1.6 WAR in 84 games as a rookie, but he had his debut cut short by oblique and back injuries. This year, he stayed healthy and started 153 of 162 games at shortstop for the Angels, putting together a breakout offensive season while continuing to provide strong defense (11 DRS) at shortstop.

Honorable Mentions: C Logan O'Hoppe (24), RP Ben Joyce (23), SP Jack Kochanowicz (23), 1B Nolan Schanuel (22)

Los Angeles Dodgers: OF Andy Pages

Age: 23

Stats: 116 G, 102 OPS+, .248/.305/.407, 37 XBH (13 HR), 46 RBI, 1.3 WAR

After hitting .371/.452/.694 with five home runs and 15 RBI in his first 15 games at Triple-A, outfielder Andy Pages earned a quick promotion to the majors, making his MLB debut on April 16.

He continued to swing a hot bat early on in the big leagues, and while he leveled off, he still put together an above-average rookie campaign for the Dodgers. If no outside additions are made, he could be the in-house favorite to serve as the starting left fielder next year alongside Tommy Edman in center field and Mookie Betts in right field.

Honorable Mentions: None

Miami Marlins: SS Xavier Edwards

Age: 24

Stats: 70 G, 124 OPS+, .328/.397/.423, 18 XBH (1 HR), 26 RBI, 31 SB, 2.0 WAR

A first-round pick in 2018 and a Top 100 prospect prior to the 2020 season, Xavier Edwards spent time in the Padres and Rays organizations before he was traded to the Miami Marlins prior to the 2023 season in a four-player deal.

Edwards took over as the Marlins' starting shortstop after veteran Tim Anderson was cut loose at the beginning of July. While he does not offer much in the way of power and is a below-average defender, his contact skills and elite speed helped him hit .328 over 303 plate appearances.

Honorable Mentions: SP Valente Bellozo (23), SP Ryan Weathers (23)

Milwaukee Brewers: OF Jackson Chourio

Age: 20

Stats: 148 G, 117 OPS+, .275/.327/.464, 54 XBH (21 HR), 79 RBI, 22 SB, 3.8 WAR

The Milwaukee Brewers signed Jackson Chourio to an eight-year, $82 million extension in December, setting a new record for the most money ever given to a player who had yet to make his MLB debut.

That gave him a clear path to a spot on the Opening Day roster, and after an up-and-down start to the year, he hit .303/.358/.525 with 25 doubles, 16 home runs, 63 RBI and 15 steals in 98 games from June 1 through the end of the year. He was the youngest player to appear in a MLB game in 2024, and he capped off his season with a two-homer performance in Game 2 of the NL Wild Card Series.

Honorable Mentions: OF Sal Frelick (24), 2B Brice Turang (24)

Minnesota Twins: SP Simeon Woods Richardson

Age: 23

Stats: 28 GS, 5-5, 4.17 ERA, 1.29 WHIP, 48 BB, 117 K, 133.2 IP, 2.0 WAR

Right-hander Simeon Woods Richardson was part of the return package the Minnesota Twins acquired from the Toronto Blue Jays at the 2021 trade deadline along with Austin Martin in exchange for José Berríos.

The emergence of Woods Richardson this season helped plug a glaring hole in the Minnesota starting rotation that was created when Sonny Gray and Kenta Maeda both departed in free agency.

Honorable Mentions: SP David Festa (24), SS Brooks Lee (23)

New York Mets: 3B Mark Vientos

Age: 24

Stats: 111 G, 135 OPS+, .266/.322/.516, 49 XBH (27 HR), 71 RBI, 3.2 WAR

Mark Vientos hit just .211/.253/.367 with a 30.5 percent strikeout rate and minus-1.1 WAR as a rookie in 2023, but beneath the surface of those less-than-stellar numbers, he flashed some elite batted-ball data with a 51.0 percent hard-hit rate and 114.9 mph max exit velocity.

He started the 2024 season in the minors with Brett Baty and Joey Wendle manning the hot corner, but he quickly played his way into the everyday job after he was called up on April 27. His breakout performance has continued into the postseason, and he is hitting .378/.410/.676 with two doubles, three home runs and 11 RBI in nine games while helping the Mets reach the NLCS.

Honorable Mentions: C Francisco Alvarez (22)

New York Yankees: SS Anthony Volpe

Age: 23

Stats: 160 G, 86 OPS+, .243/.293/.364, 46 XBH (12 HR), 60 RBI, 28 SB, 3.4 WAR

This was one of the toughest decisions in this exercise, as shortstop Anthony Volpe and catcher Austin Wells have both been significant contributors for a New York Yankees team on the doorstep of a trip to the World Series with a 2-0 lead in the ALCS.

Wells had superior offensive numbers and provided solid defense behind the plate, but it's hard to overlook a 23-year-old who started 158 games at shortstop and provided a solid mix of power, speed and standout defense.

Honorable Mentions: C Austin Wells (24)

Oakland Athletics: OF Lawrence Butler

Age: 23

Stats: 125 G, 131 OPS+, .262/.317/.490, 48 XBH (22 HR), 57 RBI, 18 SB, 3.0 WAR

Outfielder Lawrence Butler hit .211 with a 62 OPS+ and minus-0.5 WAR in 42 games as a rookie last season, and he struggled to get things going at the plate again early in the 2024 season to the point that he was demoted back to the minors.

He returned to the big leagues for good on June 18 and hit .291/.330/.565 with 20 doubles, 20 home runs, 50 RBI, 55 runs scored and 15 steals in 330 plate appearances the rest of the way. He has the tools to be a potential face of the franchise for the Athletics while they transition from Oakland to Las Vegas.

Honorable Mentions: 2B Zack Gelof (24), SP Joey Estes (22), 1B Tyler Soderstrom (22)

Philadelphia Phillies: RP Orion Kerkering

Age: 23

Stats: 64 G, 14 HLD, 2.29 ERA, 1.08 WHIP, 17 BB, 74 K, 63.0 IP, 1.6 WAR

Orion Kerkering made his MLB debut for the Philadelphia Phillies as a September call-up in 2023, and he ended up making more appearances in the playoffs (7) than he did during the regular season (3) after earning a spot on the postseason roster.

He broke camp with a spot in the 2024 bullpen and served as a reliable late-inning option alongside Jeff Hoffman, Matt Strahm and trade deadline pickup Carlos Estévez. With Hoffman and Estévez both headed for free agency, he could fill an even more prominent role in 2025.

Honorable Mentions: OF Johan Rojas (23)

Pittsburgh Pirates: SP Paul Skenes

Age: 22

Stats: 23 GS, 11-3, 1.96 ERA, 0.95 WHIP, 32 BB, 170 K, 133.0 IP, 5.9 WAR

If Paul Skenes had been part of the Pittsburgh Pirates' roster on Opening Day, he might have joined Fernando Valenzuela as the only rookies in MLB history to take home Cy Young honors.

He only allowed four earned runs in a start once, and in 14 of his 23 starts, he allowed one or zero earned runs, including two outings where he was pulled from a no-hitter. The 6'6", 235-pound flame-thrower limited opposing hitters to a .198 batting average, and his 33.1 percent strikeout rate trailed only Garrett Crochet (35.1%) among pitchers with at least 130 innings of work.

Honorable Mentions: SP Jared Jones (22)

San Diego Padres: OF Jackson Merrill

Age: 21

Stats: 156 G, 127 OPS+, .292/.326/.500, 61 XBH (24 HR), 90 RBI, 16 SB, 4.4 WAR

One of the best pure hitting prospects in the minors throughout his time rising the ranks in the San Diego farm system, Jackson Merrill made a seamless transition to the big leagues and was a breakout star on a playoff team.

He learned to play center field on the fly in the majors, playing the first pro game of his career at that position on Opening Day against the Los Angeles Dodgers in the Seoul Series, and he settled in nicely both offensively and defensively as the season progressed. He checks all the boxes to be one of the best homegrown stars in Padres franchise history.

Honorable Mentions: None

San Francisco Giants: OF Heliot Ramos

Age: 24

Stats: 121 G, 125 OPS+, .269/.322/.469, 48 XBH (22 HR), 72 RBI, 2.3 WAR

Outfielder Heliot Ramos made four different appearances on the Baseball America Top 100 prospect list, but he fell flat in his first extended MLB action, hitting .179 with 20 strikeouts in 60 plate appearances in 2023 while exhausting his rookie status with time spent on the active roster.

He started the 2024 season in the minors, but he quickly played his way into a regular role after he was promoted on May 8. Poor defensive metrics in center field (-15 DRS, -12.0 UZR/150) suggest he is better suited at an outfield corner, and he has the power to profile and arm strength to fit well in right field.

Honorable Mentions: RP Randy Rodríguez (24), SP Hayden Birdsong (22), SP Kyle Harrison (22)

Seattle Mariners: OF Julio Rodríguez

Age: 23

Stats: 143 G, 116 OPS+, .273/.325/.409, 37 XBH (20 HR), 68 RBI, 24 SB, 4.3 WAR

There is a case to be made that right-hander Bryan Woo had a better season than Julio Rodríguez, going 9-3 with a 2.89 ERA, 0.90 WHIP and 101 strikeouts in 121.1 innings over 22 starts.

However, J-Rod caught fire down the stretch, posting an .895 OPS with seven home runs, 22 RBI and six steals in 26 games in September. That gave him a third straight 20/20 season to begin his big league career, and he has already racked up 15.9 WAR in 430 games.

Honorable Mentions: SP Bryan Woo (24)

St. Louis Cardinals: SS Masyn Winn

Age: 22

Stats: 150 G, 102 OPS+, .267/.314/.416, 52 XBH (15 HR), 57 RBI, 11 SB, 4.9 WAR

Despite a less-than-stellar MLB debut in 2023 where he hit .172 with a 28 OPS+ in 137 plate appearances, Masyn Winn was still given the opportunity to stake his claim to the starting shortstop job this season.

He rewarded the Cardinals patience with a breakout season, providing more than enough offensive production to back his elite defense (14 DRS to lead all shortstops). There is a good chance he will join Jeremy Peña (HOU, 2022) and Anthony Volpe (NYY, 2023) as the only rookie shortstops to win a Gold Glove.

Honorable Mentions: 2B Nolan Gorman (24), C Iván Herrera (24), RP Matthew Liberatore (24), OF Michael Siani (24)

Tampa Bay Rays: SP Taj Bradley

Age: 23

Stats: 25 GS, 8-11, 4.11 ERA, 1.23 WHIP, 47 BB, 154 K, 138.0 IP, 1.6 WAR

Taj Bradley flashed his potential as a rookie in 2023 when he racked up 129 strikeouts and 11.1 K/9, though his swing-and-miss success was accompanied by a 5.59 ERA and 1.39 WHIP in 104.2 innings.

The development of his splitter into a reliable secondary option helped him improve in his second season, and that pitch generated a 33.0 percent whiff rate while generating a .213 opponents' batting average and accounting for 69 strikeouts.

Honorable Mentions: 3B Junior Caminero (20)

Texas Rangers: OF Wyatt Langford

Age: 22

Stats: 134 G, 111 OPS+, .253/.325/.415, 45 XBH (16 HR), 74 RBI, 19 SB, 3.9 WAR

After going No. 4 overall in the 2023 draft, Wyatt Langford hit .360/.480/.677 with 17 doubles, 10 home runs, 30 RBI and 12 steals in 44 games in his pro debut, closing out the season at the Triple-A level.

The Rangers saw enough in that abbreviated debut and during a terrific spring training to put him on the Opening Day roster, and he was a staple in left field throughout the season while also providing occasional starts in center field. Even with a 111 OPS+ in 557 plate appearances, there is a good chance he has just scratched the surface of his offensive potential.

Honorable Mentions: None

Toronto Blue Jays: 2B/SS Leo Jimenez

Age: 23

Stats: 63 G, 97 OPS+, .229/.329/.358, 15 XBH (4 HR), 19 RBI, 0.8 WAR

The Blue Jays received limited production from players under the age of 25, though Leo Jimenez did log some productive innings at the middle infield spots with second base in a state of flux and shortstop Bo Bichette missing time to injury.

He provided quality defense at second base (166.2 INN, 0 DRS, 3.0 UZR/150) and shortstop (323.2 INN, 1 DRS, 10.3 UZR/150), and he has the makings of a useful utility infielder going forward.

Honorable Mentions: IF/OF Addison Barger (24)

Washington Nationals: 2B Luis García Jr.

Age: 24

Stats: 140 G, 115 OPS+, .282/.318/.444, 44 XBH (18 HR), 70 RBI, 22 SB, 2.2 WAR

The Washington Nationals are still rebuilding, but there were some positive takeaways from the 2024 season, including the arrival of top prospect James Wood and the development of double play tandem Luis García Jr. and CJ Abrams.

García made his MLB debut back in 2020 just a few months after his 20th birthday. While he had shown some promising upside in the past, he finally staked claim to the everyday second base job and put together a career year offensively.

Honorable Mentions: SP Mitchell Parker (24), OF Jacob Young (24), SS CJ Abrams (23), SP DJ Herz (23), OF Dylan Crews (22), OF James Wood (21)