Every year, there are those rookies who we expect to make a splash right away. Think Kris Bryant, Ronald Acuna, Cody Bellinger, Aaron Judge--those guys.
Once we make it through all the service time manipulation shenanigans, there are always youngsters ready to snatch roster spots immediately, and 2020 is no exception.
Below are nine of the American League's top rookies, both at the dish and on the mound. I've ranked them in order of how quickly I expect them to make an impact. While some might take a few weeks or a couple of months to get there, all of these prospects are ready to be difference-makers in fantasy lineups right along with the real-life lineups they burst into.
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Luis Robert (OF, CWS)
Robert might be the safest best for a true breakout rookie season since he's already essentially solidified his role with the White Sox. He is currently projected to start in the Chicago outfield on Opening Day, and given his track record in the minors, it's clearly the right call.
Robert demolished minor-league pitching across three levels in 2019, slashing a ridiculous .322/.376/.624 across A+, Double-A, and Triple-A (122 games). He'll be 22 at the beginning of this MLB season, but profiles as a true five-tool player who can definitely make a run at a 30-30 season early in his career, considering he went 32-36 last year in the minors. His speed is what makes him so especially tantalizing in a field full of talented rookies.
Robert will likely start at the bottom of the lineup this season, but he could certainly push his way towards the top if he can get on base enough to be a true table-setter. Everything we've seen in the minors indicates that he can be, with the exception of his somewhat low walk rate which hovers around 5.0%. Robert can be a difference-maker right away, but exercise patience as he sees his first at-bats against big-league pitching. 25 homers, 25 steals, and a .270 batting average is on the table for his rookie season.
Jesus Luzardo (SP, OAK)
The 22-year-old lefty likely would have been a key cog for the Athletics in early 2019 if not for a shoulder injury that put him on the shelf for a few months last spring. He bounced back during the summer and worked his way up to Oakland for a few relief appearances, but at full health, he should be firmly entrenched in the A's rotation heading into 2020. Luzardo has a blue-chip pedigree and has dominated the minor leagues at every stop since 2017.
He combines a sinking 96-MPH fastball with a nasty curveball that acts as his put-away pitch, and his ability to miss bats is next level. He's averaged well over a strikeout per inning at every stop in his career while keeping his walk rate at excellent levels for someone so young and with so few innings under his belt. With all the job security in the world, it shouldn't take long for Luzardo to excel at the major league level.
Assuming his health, you can likely count on him for 150 innings as the Athletics try to manage his workload in his rookie year. That should equate to 150+ strikeouts and an ERA under 3.50 given that he'll be assisted by the cavernous constructs of the Oakland Coliseum.
Jo Adell (OF, LAA)
Adell is the right fielder of the future for the Halos, but his role at the beginning of the season looks a bit murky. Brian Goodwin is coming off a solid if unspectacular 2019 campaign, and he is penciled in as the right fielder ahead of Adell on the depth chart. The 20-year-old will likely fall victim to service time manipulation, but once he does debut he has the tools to excel right away. The Angels' top prospect has risen through the minors quickly and has shown that he's capable of flirting with a 25-25 season along with a sustainable batting average--all of this in addition to his above-average outfield play.
The big adjustment he'll need to make is in the strikeout department. At multiple stops in the minors, he's posted a strikeout rate above 25%, albeit in limited action everywhere. If he can keep the Ks under control, Adell has a well-rounded assortment of skills that can make him fantasy relevant in every format.
A.J. Puk (SP, OAK)
We got our first peek at the intimidating lefty at the end of last season following his return from Tommy John surgery. While he threw out of the bullpen there, he is definitely ticketed for the starting rotation over the long term. It's impossible not to draw comparisons to Randy Johnson, with the long hair, lanky frame, and devastating fastball/slider combo. Fortunately, it didn't look like Puk took any developmental steps backward with the surgery--he maintained his fastball speed (~97MPH) and his walk rate remained between 6-10%.
The big factor that sets Puk apart is the strikeout potential. He's been able to strike out over 30% of his opponents at almost every stop in the minors, and that's what gives him perhaps the highest long-term potential of any rookie in 2020. I think it's doubtful that Puk throws more than 130 innings this season, but he'll be an immediately useful asset whether he's in the rotation or closing out the season from the bullpen thanks to the enormous strikeout potential.
Brendan McKay (SP, TB)
McKay just squeaked under the rookie eligibility line last season, throwing 49 innings across 11 starts. The ERA (5.14) and WHIP (1.41) left a lot to be desired, as McKay actually gave up 53 hits in those 49 innings, but we got a look at the swing-and-miss stuff that cemented his status as a top prospect.
The 24-year-old has maintained an exceptional strikeout to walk ratio at every level except the majors. He posted a 4.00 K-BB ratio everywhere but Tampa, and there he still had a 3.50. The big scare here is the contact--McKay is undoubtedly a fly ball pitcher, and thanks perhaps in part to the juiced ball he posted a poor 1.47 HR/9 rate. The upside is undoubtedly there, but McKay may not be a top-of-the-line starter right away.
Nate Pearson (SP, TOR)
An arm broken by a comebacker held Pearson out for almost the entire 2018 season, but outside of that setback, he has sprinted through the minors. It's easy to see why--the 6'6" righty brings a 100-MPH heater to the table and backs it up with a plus slider, curveball, and change-up. There simply aren't a ton of holes to poke in Pearson's profile.
The big question mark attached to him this year is his arrival date. The Blue Jays added to their previously non-existent rotation with free agency, but with the exception of perhaps Hyun-Jin Ryu there are no real impact arms. Pearson will likely start in AAA, but assuming he doesn't run into any obstacles we should see him in May/early June.
Sean Murphy (C, OAK)
Murphy should slot in immediately as the Athletics' primary catcher heading into 2020, and given how thin the talent pool is at that position he should be relevant immediately. Like most catchers, you shouldn't expect much from a batting average standpoint, but Murphy has some true raw power.
Across three levels (Rookie, AAA, and MLB) Murphy smoked 15 long balls in just 237 plate appearances in 2019--good for a career-high .300+ ISO at the highest levels. That's certainly enough to work with if you're willing to wait and avoid the elite catchers on draft day. Given that the 25-year-old has never played anywhere near a full season, don't be surprised if we see plenty of off days as Murphy adjusts to the major league grind.
Kyle Lewis (OF, SEA)
While the rebuilding Mariners' lineup is mostly an enigma at this point, Kyle Lewis seems like one of the few position players locked into a spot. The 24-year-old was an elite college prospect (Baseball America's 2015 College Player of the Year) but dealt with an array of injuries early in his career.
He finally put together a solid season in 2019 at AAA, slugging 11 homers and batting .263 over 517 plate appearances. That earned him a late-season call-up, and he proceeded to smack another six homers in 18 games. However, he also posted a 38.7% strikeout rate in those 18 games, and he'll need to bring that number down if he hopes to have staying power in fantasy lineups.
Ryan Mountcastle (1B, BAL)
This 22-year-old Orioles prospect is perhaps the best bat in the entire system. After an excellent 2018 season in AA, Mountcastle spent his 2019 absolutely destroying AAA pitching with a .312/.344/.527 slash line. From everything we've seen from him in the minors, Mountcastle is ready for major league pitching. The big question is where he'll fall in the Orioles lineup once he does make the show.
After moving from shortstop to third base, Mountcastle spent much of last year getting time at first base and in the outfield. I expect the Orioles to try him out in several spots this spring because if there is one thing that's certain it's that if you can hit, they'll find a place for you. My folding money is on him settling in at first base, as there is a conspicuous and expensive lack of production from that spot in the Orioles' lineup.