First base is less often where prospects start out than where they end up, either by outgrowing more premium positions or getting pushed out by more premium defenders.

So the prospect pool tends to be light on true first basemen, who have a difficult path to the majors and a lot of pressure on their bats to perform. 

Of course, that isn't an issue for the top two on this list, who look like franchise cornerstones. It doesn't mean you should ignore Nos. 3-10, though. Sometimes, the defensive limitations that push a first baseman down a traditional prospect list mask a potent bat that can then catch the baseball world by surprise when the opportunity does arise, as happened famously with Paul Goldschmidt and more recently with Pete Alonso.

Note: This list is intended for a variety of Fantasy formats and thus weighs short-term role against long-term value. Not all of these players will contribute in 2021 — most, in fact, will not — but among prospects, they're the names Fantasy Baseballers most need to know. 

1. Andrew Vaughn, White Sox

Age (on opening day): 22
Where he played in 2019: Rookie, low Class A, high Class A
2019 minors: .278 (205 AB), 6 HR, 17 2B, .832 OPS, 30 BB, 38 K

Rare is the true first baseman who gets drafted third overall. Rarer still is the one who bats right-handed. It sheds some light on Vaughn's offensive projection, which is sky high after a college career that saw his simple swing and patient approach translate to mega production and the Golden Spikes Award for best player in 2018.

2. Triston CasasRed Sox

Age (on opening day): 21
Where he played in 2019: low Class A, high Class A
2019 minors: .256 (429 AB), 20 HR, 26 2B, .830 OPS, 58 BB, 118 K

Though the pandemic came at a critical point in Casas' development, rumor has it that he found another gear at the alternate training site, where he was forced to adapt to more advanced competition. He has a setup like Joey Votto, a follow-through like Freddie Freeman and a hitting profile not too unlike Cody Bellinger at a similar stage of development. 

3. Bobby Dalbec, Red Sox

Age (on opening day): 25
Where he played in 2019: Triple-A
2019 minors: .239 (472 AB), 27 HR, .816 OPS, 73 BB, 139 K
2020 majors: .263 (80 AB), 8 HR, .959 OPS, 10 BB, 39 K  

Dalbec lived up to his 70-grade power bat right away, helping Rotisserie players make up some ground in the home run category while positioning himself for a full-time job next year. Still, the strikeout rate blew up again after he made some strides in that area as a minor-leaguer. There's a chance he bottoms out, in other words, but what he does well he does really well.

4. Lewin DiazMarlins

Age (on opening day): 24
Where he played in 2019: high Class A, Double-A
2019 minors: .270 (455 AB), 27 HR, 33 2B, .851 OPS, 33 BB, 91 K
2020 majors: .154 (39 AB), 2 2B, .400 OPS, 2 BB, 12 K  

While he didn't make good on his first look in the role, Diaz still projects as the Marlins' eventual first baseman, boasting surprising contact skills for a player with his kind of power potential. Jesus Aguilar is under team control for a few more years, but Diaz offers superior defense if the NL DH is here to stay.

5. Seth Beer, Diamondbacks

Age (on opening day): 24
Where he played in 2019: high Class A, Double-A
2019 minors: .289 (450 AB), 26 HR, 103 RBI, .904 OPS, 46 BB, 113 K

Beer is the classic stats-over-scouts prospect whose placement on any rank list is sure to meet with derision. He has been an OPS hog in his first two years in the minors but was one of four prospects the Astros shipped away for Zack Greinke in 2019, his suspect bat speed and general lack of athleticism both raising questions.

6. Bryce Ball, Braves

Age (on opening day): 22
Where he played in 2019: Rookie ball, low Class A
2019 minors: .329 (231 AB), 17 HR, 18 2B, 1.023 OPS, 26 BB, 50 K

A 24th-round pick in 2019, Ball has obviously turned heads since then to rank as high as he does here, namely by demonstrating how in touch he is with his 6-foot-6 frame. Considerable power is the result — and with good enough vision to make him potentially more than a one-note player — though it's worth pointing out he's still pretty far down the ladder.

7. Michael Toglia, Rockies

Age (on opening day): 22
Where he played in 2019: short-season Class A
2019 minors: .248 (145 AB), 9 HR, 7 2B, .852 OPS, 28 BB, 45 K

The Rockies invested a first-round pick in Toglia a year ago, and of course, anyone who goes on to play at Coors Field has a chance to be an impact player in Fantasy. For his age, you would have expected him to deliver more at one of the lowest levels of the minor leagues, though the power and patient approach are attributes to work with.

8. Aaron Sabato, Twins

Age (on opening day): 21
Where he played in 2019: not under contract

Having been drafted just this year (27th overall), Sabato has no minor-league production to point to, which makes me reluctant to go hog wild for him — especially since, as a right-handed hitting first baseman, he'll need to knock the cover off the ball to carve out a path. But he's supposed to have the kind of bat speed and loft to do that.

9. Pavin Smith, Diamondbacks

Age (on opening day): 25
Where he played in 2019: Double-A
2019 minors: .291 (440 AB), 12 HR, 6 3B, 29 2B, .835 OPS, 59 BB, 61 K
2020 majors: .270 (37 AB), HR, 3B, .746 OPS, 5 BB, 8 K    

Though all but forgotten as the seventh overall pick in 2017, Smith did ultimately ascend to the majors this year and got to play fairly regularly over the final two weeks. He's a contact-over-power guy, which is suboptimal at first base especially, but he may have turned the corner over the final two months of 2019, hitting .350 with seven homers and a 1.008 OPS.

10. Sherten Apostel, Rangers

Age (on opening day): 22
Where he played in 2019: low Class A, high Class A
2019 minors: .251 (418 AB), 19 HR, 18 2B, .779 OPS, 51 BB, 120 K
2020 majors: .100 (20 AB), 2B, .293 OPS, 1 BB, 9 K

If a quick glance at Apostel's stat line doesn't do it for you, I offer three reasons for hope:  He was rushed through the system, his plate discipline was excellent in the lower minors, before the Rangers encouraged him to be more aggressive, and he may ultimately wind up at third base. Power is his most intriguing tool for Fantasy, as easy as it is to come by.