Top 10 First Base Prospects (2020 Preseason): Often Overlooked, Is There Value To Be Found?


When it comes to prospects first base is often a position that is overlooked. Sure they emerge, but often times it’s a player who shifted from another position (like third base) as opposed to a pure prospect at the position. Of course that doesn’t mean that someone couldn’t emerge, so who are the names we should know? Are there any surprises emerging? Let’s take a look:


1.Andrew VaughnB+Chicago White Sox
2.Triston CasasB+Boston Red Sox
3.Evan WhiteBSeattle Mariners
4.Michael TogliaB-Colorado Rockies
5.Tyler NevinC+Colorado Rockies
6.Lewin DiazC+Miami Marlins
7.Ryan MountcastleC+Baltimore Orioles
8.Gavin SheetsCChicago White Sox
9.Jared WalshCLos Angeles Angels
10.Seth BeerCArizona Diamondbacks

1) Andrew Vaughn – Chicago White Sox
Grade – B+

In many systems Vaughn would be considered the top prospect, but he takes a backseat to Robert in Chicago.  Selected third overall in ’19, Vaughn reached High-A in short order and showed power (17 doubles and 6 HR over 245 PA) and a strong approach (12.2% walk rate, 9.3% SwStr%) along the way.  Already 21-years old his ascent could continue to come quickly, with an arrival at some point in 2021 seemingly likely.

It’s not all positive, as there are going to be questions whether or not his power will translate given his size (he’s listed at 6’0”).  As a first baseman/designated hitter type that’s going to loom large, but how the production translates this season (where he should reach Double-A, at least) will be telling to his long-term outlook.

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2) Triston Casas – Boston Red Sox
Grade – B+

The 2018 first round draft pick got his first real time of professional baseball, after injuries limited him to 4 AB in 2018.  There’s no questioning his power potential and ability to draw walks, the question will be if the 20-year old will be able to make enough contact to tap into it.  Playing most of the season at Single-A, he showed signs of improving his strikeout rate as the season progressed:

  • First Half – 26.44%
  • Second Half – 20.26%

That type of improvement shows his significant upside, because if he can maintain the improved rate with the other skills he has difference-making potential.  While he’s at least a year away, he has the potential to put it all together and start moving quickly through Boston’s system.

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3) Evan White – Seattle Mariners
Grade – B

White signed an extension in the offseason, which cleared his spot in the Opening Day lineup despite playing 2019 at Double-A (365 AB at the level in ’19).  There had been questions about his power potential, but he’s begun tapping into it as he’s developed (18 HR in ’19) and it should continue to grow.  However at what expense does that power come in terms of his approach?  Just look at the numbers:

  • Strikeout Rate – 23.0%
  • Walk Rate – 7.2%
  • SwStr% – 12.4%

He’ll turn 24-years old before the 2020 season ultimately gets underway, so it’s hard to anticipate a significant step forward in his development.  With the potential to be exposed as he continues to advance, keep that in mind before assuming he’s going to excel immediately.

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4) Michael Toglia – Colorado Rockies
Grade – B-

Selected in the first round of the 2019 draft, the switch hitter has tremendous power potential and already showed a strong eye at the plate (15.9% walk rate over 176 PA at Low-A).  The question is going to be the strikeout rate, as the 6’5”, 226 lbs. slugger is a lock to have significant swing and miss in his game (12.7% SwStr% in his first taste of professional baseball). 

He has a history in the outfield, but by all reports he is a plus defender at first base and figures to stick there long-term.  He has the potential to move quickly and if he proves he can keep his strikeouts in check his stock will rise significantly.

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5) Tyler Nevin – Colorado Rockies
Grade – C+

There have been questions about his power potential, but having exploded for 8 HR over 110 AB in August is going to catch your attention.  How “real” was the outburst or was it an outlier remains to be seen, but he showed a strong approach at Double-A (16.7% strikeout rate, 12.0% walk rate) and if there is any truth behind the surge he could really make an impact.  With his future being at first base (he has primarily been a third baseman to this point) he needs to prove that power is for real.’

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6) Lewin Diaz – Miami Marlins
Grade – C+

Acquired in the trade that sent Sergio Romo to Minnesota, Diaz totaled 27 HR (as well as 33 doubles and 2 triples) playing at High-A and Double-A.  There’s no questioning the power potential he possesses, though his weight is going to be a concern and while he hasn’t had strikeout problems yet it’ll be something to watch as he continues to advance (he had a 12.1% SwStr% at Double-A). 

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7) Ryan Mountcastle – Baltimore Orioles
Grade – C+

Mountcastle was once a highly touted prospect, and there’s no questioning the power potential he brings to the table (25 HR, 61 total extra base hits over 520 AB at Triple-A last season).  The question is going to be whether or not he can consistently make enough contact to tap into it.  Last season he posted a 15.7% SwStr% while at Triple-A, and that’s a number that could further regress upon reaching the Majors.

There’s also a question as to where he’ll ultimately fit defensively, as he’s moved off of shortstop instead seeing time at first base (84 games), third base (9 games) and in the outfield (26 games) last season.  Assuming he can hit for power, the Orioles are going to find a spot for him.

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8) Gavin Sheets – Chicago White Sox
Grade – C

It was a tale of two halves for Sheets, playing the season at Double-A:

  • First Half – .246/.313/.352
  • Second Half – .289/.377/.478

Reports are that he began using the lower half of his body more as the season progressed, allowing him to tap into his power and drive the ball (14 doubles, 1 triple, 9 HR after the All-Star Break).  If that power surge proves to be real, when coupled with a strong approach (8.9% SwStr%, 10.2% walk rate) the upside is real.  It’s very possible he takes a step up and sees his grade improve at least into the C+ range.

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9) Jared Walsh – Los Angeles Angels
Grade – C

Playing the year at Triple-A Walsh hit .325 with 36 HR over 382 AB and got a taste of the Majors, and after hitting 29 HR across three levels in ’18 it’s hard to say that the power isn’t for real.  Pairing that with a solid approach, with a 10.5% SwStr% helping lead to a 25.3% strikeout rate and 13.0% walk rate, and it’s obvious that he deserves an opportunity.  The fact that he can also be utilized on the mound, operating as a two-way player, only adds to the appeal though the ceiling is limited overall and it’ll be difficult for him to find playing time on a crowded roster. 

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10) Seth Beer – Arizona Diamondbacks
Grade – C

Arizona acquired Beer as part of the Zack Greinke trade, and his power potential is his best trait and he’s shown it early in his career (38 HR since being drafted in ’18).  His 11.3% SwStr%, split between High-A and Double-A, isn’t unreasonable though it rose to 12.3% in 381 PA at Double-A and could continue to rise as he faces more advanced pitching.  That will be something to watch, especially given the lack of speed and obvious fit defensively (he has split time between first base and outfield thus far).

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Sources – Fangraphs,,

Make sure to check out all of our 2020 prospect rankings:

AL EastAL CentralAL West
Baltimore OriolesChicago White SoxHouston Astros
Boston Red SoxCleveland IndiansLos Angeles Angels
New York YankeesDetroit TigersOakland A's
Tampa Bay RaysKansas City RoyalsSeattle Mariners
Toronto Blue JaysMinnesota TwinsTexas Rangers
NL EastNL CentralNL West
Atlanta BravesChicago CubsArizona Diamondbacks
Miami MarlinsCincinnati RedsColorado Rockies
New York MetsMilwaukee BrewersLos Angeles Dodgers
Philadelphia PhilliesPittsburgh PiratesSan Diego Padres
Washington NationalsSt. Louis CardinalsSan Francisco Giants
PositionLast Updated
First Baseman--
Second Baseman04/15/20
Third Baseman04/20/20


  1. Bryce Ball is going to outperform everyone on this list outside of Vaughn (and even then I think he may). I get serious Bellinger vibes from Ball


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