Best MLB player at each age for 2021 season: From 18-year-old Jasson Dominguez to 41-year-old Rich Hill

Spring training is here. Camps are in full swing across Arizona and Florida, and the slow-paced offseason has been replaced with real live baseball. To celebrate baseball’s return, we’re going to look at the best baseball player at each age from 18-42. We also recently took at look at the top 25 players under 25 and will have our list of top 100 players for the 2021 season next week.

For this exercise specifically, we’re going to highlight the best 18-year-old, the best 19-year-old, the best 20-year-old, all the way up to the best 42-year-old. We’re picking players based on their expected production in 2021, not their careers to date. Each player’s age on June 30, the approximate midpoint of the season, is used as his season age. Come with me, won’t you?

Age 18: Jasson Dominguez, Yankees

A whopping 212 players made their MLB debut in 2020, nearly as many as 2019 (261) and 2018 (247) despite 102 fewer games per team. None of those 212 players were 18 years old, however. Alex Rodriguez remains MLB’s last 18-year-old (he appeared in 13 games as an 18-year-old with the 1994 Mariners), and before him, you have to go back to Jose Rijo with the 1984 Yankees. We’ve seen a number of 19-year-olds in recent years. It’s been more than a quarter-century since the last 18-year-old though.

In all likelihood we will not see an 18-year-old in the major leagues in 2021. Dominguez, who our R.J. Anderson ranked as the No. 2 prospect in New York’s system, is the best 18-year-old player in the world, and he’s yet to even play a professional game. The Yankees gave him a $5.1 million bonus as an international free agent out of the Dominican Republic in 2019, and the pandemic wiped out his highly anticipated debut in 2020. Dominguez will instead debut this year and his workout videos are already the stuff of legend.

Other notable 18-year-olds include Royals outfield prospect Erick Pena and and Athletics shortstop prospect Robert Puason, who also signed in 2019 and will make their pro debuts this summer.

The best under-18 player in the world is likely Nationals shortstop prospect Armando Cruz. They gave him a $3.9 million signing bonus out of the Dominican Republic in January, and Baseball America describes Cruz as a “defensive wizard.” MLB’s last 17-year-old player was Jay Dahl with the 1963 Houston Colt .45s. Dahl allowed seven runs in 2 2/3 innings in his only MLB game.

The Giants gave Luciano a $2.6 million signing bonus in 2018 and he was the youngest player at an alternate site last year. Our R.J. Anderson ranks Luciano as the No. 2 prospect in San Francisco’s system and says he has “star-level upside thanks to a projectable frame; great bat speed; and natural loft.” It’s not out of the question that Luciano makes his MLB debut this season, though I don’t think it’ll happen after the weirdness of last year. Other notables in the age-19 group include catching prospects Francisco Alvarez (Mets) and Diego Cartaya (Dodgers), Blue Jays infield prospect Orelvis Martinez, and Rockies outfield prospect Vac Zeen.

The best prospect in baseball is also the best 20-year-old player in the world. Franco spent last season at the alternate site and the Rays believe in him so much that they carried him on their postseason taxi squad. You don’t do that unless you’re willing to put the player on the field when you’re playing for all the marbles. Our R.J. Anderson says Franco has the tools to be a “special, special player,” and it is all but certain he will make his MLB debut at some point in 2021 (likely later in the year for service-time reasons). Padres shortstop prospect C.J. Abrams and Mariners outfield prospect Julio Rodriguez are the runners-up in the age 20 group.

We’ve been very spoiled in recent years. Players like Ronald Acuna Jr., Juan Soto, and Fernando Tatis Jr. have come up at ages 19-20 and been immediate impact players. They are the exception, not the rule, and the best 21-year-old player in the world is a player who has yet to make his MLB debut. Of course, had Kelenic agreed to a below-market extension, he would have made his MLB debut in 2020. Former Mariners president Kevin Mather was nice enough to admit that on camera. Our R.J. Anderson says Kelenic is an “advanced hitter who should contribute across the triple-slash categories.” 

Kelenic’s primary competition in the age-21 group are Tigers first base prospect Spencer Torkelson (No. 1 pick in 2020 draft) and Royals shortstop prospect Bobby Witt Jr. (No. 2 pick in 2019). Shoutout to Vanderbilt right-hander Jack Leiter (Al’s son), who could go No. 1 overall in this summer’s draft.

Age 22: Juan Soto, Nationals

Finally, some big leaguers. The age 22 group is stacked — Fernando Tatis Jr. is Soto’s primary competition (and was ahead of him in our staff ranking of the top 25 players under 25), and shoutout to Vladimir Guerrero Jr., Sixto Sanchez, Dylan Carlson, and Padres pitching prospect MacKenzie Gore — but Soto is the obvious pick for me. What he’s done these last three seasons is nothing short of historic. Here’s where Soto ranks among the 77 players with at least 1,000 plate appearances through their age-21 season:

• Batting average: .295 (23rd)
• On-base percentage: .415 (5th)
• Slugging percentage: .557 (4th)
• OPS+: 151 (6th)

The five players ahead of Soto on the OPS+ list: Mike Trout (166 OPS+), Ted Williams (161 OPS+), Jimmie Foxx (156 OPS+), Rogers Hornsby (155 OPS+), and Ty Cobb (153 OPS+). Five of the best hitters who ever live, basically. I fully expect Tatis to be a top-10 player in baseball in 2021, but Soto might be the best hitter on the planet right now. He is outrageously good.

Age 23: Ronald Acuna Jr., Braves

Acuna and Soto are going to be compared to each other for a long, long time, and fortunately we don’t have to pick between them for this exercise. Soto leads his age group and Acuna leads his. Since arriving in 2018, Acuna is a top-20 player by WAR (12.1) and a top-20 hitter by OPS+ (133). Bo Bichette, Luis Robert, and Orioles catching prospect Adley Rutschman, the No. 1 pick in 2019, are the runners-up in this age group among position players. Ian Anderson, Jesus Luzardo, and Dustin May are the standouts on the mound.

If you’re going for name value, Rafael Devers or Gleyber Torres is probably the pick here. If you like majestic dingers, it’s Yordan Alvarez or Eloy Jimenez. Partial to pitchers? Then Julio Urias is your guy. I’m going with Albies, who has been the best all-around player in this age group to date. Trent Grisham put himself on the map last year, and don’t be surprised if Pirates third baseman Ke’Bryan Hayes emerges from this age group next year. He’s an all-world defender at the hot corner and there’s more pop in his bat than many projected during his prospect days.

Bellinger makes the age-25 group by 13 days. Had he been born two weeks earlier, he’d be in the age-26 group, in which case the age-25 group would go to Cardinals ace Jack Flaherty. Bellinger had a down 2020 season but he’s hardly alone in that regard, and he’s a freakish athlete would could put together another MVP season in 2021 and no one would blink twice. Reigning AL Rookie of the Year Kyle Lewis, Willy Adames, and Alex Verdugo are the other notables in the age-25 group. Zac Gallen is the best this group has to offer on the mound.

The reigning AL Cy Young winner ranks fifth in WAR (7.8) and second in strikeouts (381) the last two seasons, and is a fairly easy pick. That’s impressive because this age group includes fellow aces Walker Buehler and Lucas Giolito, as well as notable position players like Pete Alonso, Carlos Correa, Brandon Lowe, Austin Meadows, and Dominic Smith. Shohei Ohtani belongs to the age-26 class as well and I sure hope we get to see him excel as a two-way player in 2021. Please stay healthy, Shohei.

Lots of really good players in this age group, including Jose Berrios, Max Fried, Tyler Glasnow, Josh Hader, Ketel Marte, and Dansby Swanson. Ultimately, it comes down to one of three star infielders. Let’s compare their 2019-20 numbers side-by-side real quick:

Alex Bregman, Astros	870	.284/.408/.562	153	47	5	10.1
Francisco Lindor, Mets	920	.277/.335/.489	114	40	28	6.1
Corey Seager, Dodgers	773	.282/.342/.514	125	34	2	5.4

Bregman has the best numbers, clearly, so I guess the question is how much do you want to ding him for the sign-stealing scandal? Because MLB’s investigation “revealed no violations” in 2019, I won’t ding Bregman at all for the sign-stealing scandal. It’s water under the bridge at this point. He’s the pick, though I do love Lindor and Seager. I’d take them on my team any day.

It’s unfair players to players as good as Tim Anderson, Xander Bogaerts, Matt Chapman, Michael Conforto, Bryce Harper, Manny Machado, Jose Ramirez, Trevor Story, and Trea Turner that they’re stuck in the same age group as Betts. Mookie does the baseball equivalent of posterizing opposing teams on the nightly basis, either at the plate, in the field, or on the bases. There’s no weakness in his game. He’s great at everything and is so very easy to like. It’s sort of amazing MLB hasn’t found a way to get him in every commercial and on every billboard. Mookie should be the face of baseball.

Age 29: Mike Trout, Angels

You know you’re good when you hit .281/.390/.603 with 17 home runs in a 60-game season and it legitimately qualifies as a down year. Trout had his lowest on-base percentage since 2014 and his lowest slugging percentage 2016 last year, and yet he was still among the game’s best players and a top-five finisher in the MVP voting. His 20s are nearing an end though — Trout turns 30 in August. This age group includes two former MVPs (Kris Bryant and Christian Yelich), and former MVP runner-up (Aaron Judge), and several other really good players (Willson Contreras, Jeff McNeil).

The age-30 group features two legitimate headliners in Cole and Rockies-turned-Cardinals third baseman Nolan Arenado. There is no wrong answer here and if you feel strongly it should be Arenado, that’s cool. Totally justifiable. Cole has a solid argument for being the most dominant pitcher in the world right now — his 420 strikeouts the last two years are 39 more than anyone else — and that guy will never look out of place in an exercise like this. Marcell Ozuna, J.T. Realmuto, and Cole’s former UCLA teammate Trevor Bauer are the other notables in the age-30 group.

Tough few age groups for star third basemen. Arenado was edged out by Cole in the age 30 group and Freeman beats out Anthony Rendon in the age-31 group. They’re both excellent, of course, but I’m comfortable giving the nod to the reigning NL MVP, the guy who hit .341/.462/.640 and amassed 3.2 WAR in a 60-game season last year. This age group also includes two former MVPs who have battled injuries the last few years (Jose Altuve and Giancarlo Stanton), a postseason legend (Madison Bumgarner), and the underappreciated Kyle Hendricks.

If you built a baseball player in a lab, he’d look a lot like LeMahieu. He rarely strikes out, he posts some of the highest exit velocities in the game, he’s excellent defensively, and he’s about as low maintenance as it gets. Back-to-back MVP-caliber seasons earn LeMahieu the nod here over a former World Series MVP (Stephen Strasburg), arguably the best reliever in the game (Liam Hendriks), and others like Yasmani Grandal, Starling Marte, and Whit Merrifield.

For my money, deGrom is the best pitcher in baseball. He failed to join the ultra-exclusive back-to-back-to-back Cy Young winner club last year (only Hall of Famers Randy Johnson and Greg Maddux have done it), but he was still excellent, and I’d bet on him being excellent again in 2021. The age-33 group includes one no-doubt future Hall of Famer (Clayton Kershaw), two players who are starting to put themselves in the Hall of Fame conversation (Aroldis Chapman and Paul Goldschmidt), and the reigning AL Cy Young runner-up (Kenta Maeda).

Tough call here. Abreu had a monster 2020 season en route to being named AL MVP. He led the league in hits (76), runs driven in (60), slugging percentage (.617), and total bases (148). Yu Darvish, Abreu’s primary competition, was the NL Cy Young runner-up with a 2.01 ERA and 93 strikeouts in 76 innings. This could go either way. Given Darvish’s tendency to struggle — “struggle” — when joining a new team (Cubs in 2018, Dodgers in 2017, even the Rangers in 2012 to some degree), I’m comfortable giving it to Abreu over the San Diego-bound Darvish. Other notables in the age-34 group include Michael Brantley, Carlos Carrasco, Lance Lynn and Hyun-Jin Ryu.

We’re starting to reach the ages where MLB teams say thanks for your interest in playing for us, but no thanks. Only 37 34-year-olds appeared in a game last year and only about 15 of those 37 are certain to see big-league action in 2021. Donaldson is the best and most well-compensated of those 15. Other notables include Lorenzo Cain, Johnny Cueto, and Carlos Santana. Jake Arrieta, Matt Carpenter, and Corey Kluber could make this conversation more interesting with dead cat bounces. 

The three-time Cy Young award winning might — might — be entering his decline phase. Last year was his worst season in several years. It was also a bizarre 60-game season, during which Scherzer batting nagging lower body injuries, so who knows? I won’t bet against him in 2021. Scherzer is an easy call here over Justin Turner and Andrew Miller, who are both still pretty darn good. Special shoutout to Daniel Bard. His comeback is truly incredible.

Joey Votto is on very the short list of the best hitters in baseball over the last 10-15 years, though he is no longer that guy at age 37, so Greinke gets the nod here as a still comfortably above-average workhorse starter. Veteran starters Jon Lester and Charlie Morton are among the other notables in the age-37 group, as are Yuli Gurriel and Brett Gardner.

The two best 38-year-olds won’t play in 2021 — Justin Verlander is rehabbing from Tommy John surgery and Robinson Cano is serving a performance-enhancing drug suspension — which takes them out of the running here. Miguel Cabrera is a slam dunk first-ballot Hall of Famer, but he is no longer an impact player. As such, I’m going Molina here, even though he is on the decline. I think he’s a better catcher than Cabrera is a first baseman/DH at this point. Truth be told, J.A. Happ might be the best 38-year-old in baseball in 2021, though I’m comfortable giving the nod to Molina.

Cleveland recently re-signed Oliver Perez to a minor-league contract, and if he doesn’t make the team, Wainwright will be the only 39-year-old in baseball this season. He gets the nod here by default, not that he is undeserving. Wainwright remains an effective starter who isn’t out of place in a contender’s rotation. Recent retirees Adrian Gonzalez, Ian Kinsler, and James Shields belong in the age-39 group as well.

Cruz is one of the best hitters in baseball (he’s getting better with age, remarkably) and also very likely to be the only 40-year-old on a major-league roster in 2021. There’s not even another 40-year-old in a spring training camp this year. Cruz’s top competition for this spot are the recently retired Jose Bautista, CC Sabathia, and Ben Zobrist, so yeah. Cruz gets it and he is very deserving, lack of competition aside.

Albert Pujols will go down as one of the best hitters in history, but this is not a career accomplishments list, it’s a “who will be the best player in 2021?” list. Pujols has been replacement level or worse the last few years while Hill is a legitimately above-average pitcher, though he’s a lock to miss time with injury each year. Whatever innings he gives you will be excellent though. 

Barring a major surprise, there will be no 42-year-olds in MLB this year, so we’re dipping into the retired player pool. Beltre is a future Hall of Famer, and even though he last played 2018, I’m comfortable saying he’s the best 42-year-old player in the world right now. Other candidates include John Lackey, Cliff Lee, Victor Martinez, Chase Utley, and Jayson Werth.

Bartolo Colon and Ichiro Suzuki were the last 43, 44, and 45-year-old players to appear in an MLB game. The last player age 45-plus? Jamie Moyer, of course. He played his final season at age 49 in 2012. Force me to pick, and I’d go with Hall of Famer Mariano Rivera as the best 45-and-over baseball player in the world right now. I could see Rivera, now 51, going out to the mound and breaking bats with his near perfect mechanics and exquisite command of his cutter, or at least not embarrassing himself.