Post All-Star Prospect Rankings – First Base

Trevor Hooth has you covered with his mid-season First Base prospect rankings

I bet you were expecting the fantastic Travis Shere or Adam Lawler to bring you prospect rankings today, but surprise! You can look back at the rankings they have already completed here:


Top 100 Hitters Top 20 1B Top 25 SS
Top 100 Pitchers Top 25 2B Top 25 OF
Top 20 C Top 25 3B Top 50 OF


So, first base. These are the big boys with even bigger pop, usually. It may not come with as many asterisks as the catcher position, but there are still plenty to consider. A lot of players move to first during their career. For example, I expect (at least) one of Nolan Gorman, Malcolm Nunez, or Elehuris Montero from the Cardinals farm to transition from third to first in the coming years.

Speculation, however, does little good. These guys on this list are the born and bred first basemen. With that in mind, you can look around at other lists and guys are listed as a first baseman, yet their defensive innings are coming elsewhere. Ryan Mountcastle is an example of this. He is the top first baseman per MLB Pipeline, yet in his career, he has 1,903 innings at shortstop, 1,111 innings at third base, and 528 innings at first. He is not on this list.

Who is on the list, you ask? Great question! Here we go.


1. Andrew Vaughn, CWS, Age: 21, BAL


Vaughn was just drafted third overall and has six professional games under his belt. The University of California product is what is known in the baseball biz as ‘really freaking good’. For those unfamiliar, that term means he is really freaking good. He hit .600 with a homer in three games in the Arizona League before being promoted out of rookie ball to Class A Kannapolis. In his first five games at the new level, he has homered and walked four times. In the interest of fairness, Vaughn also struck out six times and was hitting .235. But I mean come on, look how pretty this swing is:

He is a college bat, and he is a patient hitter. Vaughn’s career is just getting started, but it is going to be fun to watch. I don’t know that anyone from this 2019 draft class will beat Adley Rutschman, but if anyone will have a shot it is Vaughn.


2. Triston Casas, BOS, Age: 19


Like Vaughn, Casas is another former first-round draft pick. He was selected 26th overall by the Boston Red Sox. Unlike Vaughn, Casas was taken out of high school. He was limited to two games in his draft year due to an injury to his right thumb he sustained from diving for a ball at third base. In his first full year, the 6’4″, 238-pound teenager is slashing .264/.345/.520 with 15 homers through 76 games with the Red Sox Class A affiliate. That is good for a wRC+ of 142. To this point in his first full season, he has struck out 83 times and walked 34. Casas is big and he has soft hands at first. For the most part, though, he is still very raw. His power will be the focal point of his offensive game, and he will need to continue to refine that as he moves up the ladder. It will take another few years before the is swinging in Fenway, but if he matures quickly I could see him making a roster bid in 2021, however that is unlikely.


3. Brent Rooker, MIN, Age: 24


Rooker is the first guy on this list that should see time in the majors this year. He is an okay defender, but he should be serviceable enough at first even though many believe his best defensive position is DH. If you are going to buy stock in Rooker it is because of his offensive upside. He is a pure power threat with the strikeout rate to prove it. In 2018, he hit 22 homers with 150 strikeouts in 130 games at the Double-A level. This year, he is 62 games in with 14 homers and 91 strikeouts at Triple-A. The big difference is that his 2019 slash line of .286/.406/.550 looks a lot better than his .254/.333/.465 line from 2018. That improvement is good for a 20 point jump in wRC+ for Rooker to put him at 144 for the season. Rooker’s progression and evolution are what makes me so high on him. He might be destined for a life as a DH, and he might not set the world on fire when he first gets to the majors, but make no mistake Rooker will become a respectable power threat in the MLB.


4. Evan White, SEA, Age: 23


White is yet another former first-round draft pick this group. White was taken 17th overall by the Mariners in 2017. The Kentucky product brought with him an advanced approach that makes him a top hitting talent for the position. After hitting over .300 in Class-A last year, he got 18 at-bats at the Triple-A level. He’s spent this year in Double-A, where he is hitting .295/.352/.483 with 11 homers and a 127 wRC+ in 58 games. This year is the most power White has shown in his professional career, which is a very positive step. His glove has long been his calling card, but if he can develop the pop in his bat a little more he can become a real threat. White has a great ability to put the ball in play, but he also has shown improved power. His ISO is up to .188 from .155 last year. Come Spring Training next year White should be vying for a spot on the Seattle Mariners roster.


5. Bobby Bradley, CLE, Age: 23


For the most part, I really wanted to avoid guys who have already debuted in the majors. Bradley has already done that and is right now still on the Indians roster. But, with only 11 games in the majors he still belongs on this list. The reason I made the exception here is that Bradley is so intriguing. In 67 games with Triple-A Columbus he has slugged 24 homers. His MLB career has started slowly with him slashing .219/.265/.375. However, his performance in Triple-A suggests that should improve. The biggest fault with Bradley will be his strikeout rate. His strikeout rate is over 30 percent across both levels this year. Bradley was off to a hot start in the power department in 2019, but he will have to adjust and tap into that power in order to improve.


6. Nate Lowe, TB, Age: 24


Lowe has worked his way into relevance after his selection in the 13th round in 2016. He has shot up the Rays farm system and has also debuted this year. Through 14 games in the majors he is slashing .240/.316/.400 with two homers. Lowe was just recalled recently so he will have time to improve on that. In Triple-A this year he slashed .290/.419/.519 with 12 homers and 50 walks in 68 games. He has a patient approach at the plate that will translate to a lot of walks, though admittedly the 16.8 % walk rate is high for his career. He hovered around a 10% walk rate previously.  Lowe has good contact ability too so he shouldn’t be striking out a ton as he gets more at-bats in the majors.


7. Matt Thaiss, LAA


This will end the trio of players who have debuted in the majors already. Thaiss has three games under his belt in the majors and a bright future ahead of him. He earned his call-up after slashing .274/.390/.477 with 14 homers through 79 games at Triple-A. Thaiss has made deliberate attempts to access the power in his swing in recent years and it has worked. In 133 games in 2017, he hit nine homers and in 125 games in 2018 he hit 16 long balls. He was on pace to crush that this year. He has proved everything he needs to prove at Triple-A so it is up to him to adjust in the majors. If he can get consistent at-bats he will be able to work towards becoming a reliable bat. I’m not personally in love with Thaiss’ upside, but he has some at least. There is little doubt that he will turn into a productive MLB first baseman.


8. Seth Beer, HOU, Age: 22


There was a lot of buzz around Beer’s bat entering the 2018 MLB Draft in which the Clemson product was drafted in the first round. He is listed as an outfielder in many different places, but he has played more games at first base. That is a good place for him because he has a  fantastic ability to hit the baseball. In his first taste of Double-A this year he is slashing an impressive .319/.413/.542 with 10 homers and a 161 wRC+ through 45 games with Corpus Christi. He spent the first part of the season in High A. If there is anything Houston can do for players it is accelerate their development. That is what they did for Beer right from the start. Small tweaks have allowed him to make better contact at all parts of the plate, which has helped him raise his ISO over the .200 mark this year. When all is said and done he might end up as a DH, but his defensive home could turn out to be first base. At the rate he is hitting the ball, he has a legitimate shot to debut with the Astros in 2020.


9. Grant Lavigne, COL, Age: 19


There’s a lot to like about Lavigne which is what made him a CBA pick in 2018. He showed his talent in the Rookie League last year, but his production has slowed at Class-A. At only 19, hopefully his raw power will develop into something more. Right now he is having his share of struggles and is hitting only .246 with five homers with 85 strikeouts in 84 games. However, his .350 average in 59 games in his draft year shows what he could turn into. With his raw power and a potential home at Coors Field, there is the potential for a high ceiling. He creates very nice bat speed out of his 6’4″ 220-pound frame. He is young, he is raw, and he will take some time to develop into a productive player. That should be around 2022 if he can turn things around soon.


10. Pavin Smith, ARI, Age: 23


Smith has taken a step back in a lot of people’s minds after being a first-round draft pick in 2017. The pessimism is due to his 2018 season in which he struggled through the Advanced-A season. This was a big disappointment after the hitting ability he displayed before the draft. Arizona has continued to move him along, so he is playing for Double-A Jackson right now and slashing .259/.334/.407. He is still showing a good approach as he walks a lot and doesn’t strike out a ton. The issue is he hasn’t been making the hardest of contact. Smith has shown improvements this year in that department, bringing his ISO up to .148 this year. With all of the hype around Smith, his performance comes with a harsher look. For instance, MLB Pipeline says he needs to hit for more power to be more than a bench bat. I don’t believe that to be true. I think Smith can become a good hitter, but that doesn’t necessarily mean he has to have a ton of power. If he can tap into his swing he can be a solid contributor to a lineup. That looks like it will be a long road, but not an impossible one to travel. That puts his ETA, in the best-case scenario, around 2021 though it’s possible he could sneak into Arizona a year before in a limited capacity.


11. Tyler Nevin, COL, Age: 22


Yet another Rockies first baseman who was stellar last year, but is currently struggling through his 2019 season. Nevin is a lot closer than Lavigne, though. After a standout year in Advanced-A ball last year he was assigned to the Arizona Fall League and now he sits in Double A. Nevin is slashing .239/.338/.339 with Hartford so far. It is disappointing and a huge step back for him. The one positive is that his walk rate has skyrocketed up to over 12 percent this season. He will be a hitter more for average than power and that will continue. Like Lavigne, a poor season will set back Nevin’s path to the majors. Once he starts to put it together again in Hartford he will be back on the path. However, for now, he is stalled. At this point, he could have a chance to crack the Colorado roster in 2021, and it will be up in the air how good he can be.


12. Lewin Diaz, MIN, Age: 22


Diaz has a lot of power and a lot of ability to hit. He has spent most of the season in Fort Myers slashing .290/.333/.533 with 13 homers in 57 games. That was enough to get him the call up to Double-A where is excelling early on. After 18 games he is slashing .319/.367/.597. Diaz swings from the left side from a nice 6’4″ 225-pound frame. Outside of last season, he has been performing at each level, but this year is statistically the best of his career. That poor performance in 2018 has dropped him out of several lists, though he is still a name to watch at the first base position. There is a lot to like with Diaz moving forward, and he is a lot closer to the majors than he appears. If he can continue to hit like this at the Double-A level he could be at Triple-A before the year is over with a chance to reach Minnesota by 2020.


13. Nick Pratto, KC, Age: 20


I want Pratto to be a lot higher on this list, but he doesn’t fit that high. He is a former first-round draft pick with high upside, but he is struggling this year. at High-A Wilmington Pratto is slashing .174/.269/.270 and that might be the best part of his season. Part of his struggles this year can be contributed to his 34.8 percent strikeout percentage. The 20-year-old has a long way to go in his development. Since the Royals will be trying to develop him, Pratto will always draw comparisons to Eric Hosmer, but that’s not fair. One thing to like about Pratto’s game is his ability to run the bases. That fits right in with Kansas City. There isn’t a ton to say here. He is young, he has potential, but he is struggling.


14. Gavin Sheets, CWS, Age: 23


Sheets doesn’t get enough credit for his ability to hit the ball. For his minor league career, he is slashing .283/.358/.407, but the issue is he does not have the pop in his bat that the position generally demands. Although, his power is starting to shine through a little more with his career-high 11 homers this season. He has a very good frame to hit from, but he still needs to work on developing more power. Even without it, he could be a decent contributor at the back end of a future White Sox lineup. When it boils down to it, Sheets puts the bat on the ball and he doesn’t strike-out a ton.


15. Michael Toglia, COL, Age: 20


Toglia is the second of two first baseman to be selected in the first round of the 2019 draft. At 20 years old he is not the most polished player, but he has some great upside to him. Immediately it is easy to notice his size. You try ignoring a 6’5″ 226-pound guy. The switch hitter is a power threat, but still working on developing more pop. During the first 17 games of his career he is slashing .222/.347/.444 with three homers. His power is already showing through in short-season A ball. If he can make consistent contact there is a lot to love about his power potential.


16. Ibandel Isabel, CIN, Age: 24


After spending the first several years of his career in Los Angeles Isabel was traded to the Reds. Isabel will have a tough time winning the first baseman job in Cincinnati as long as little known Joey Votto is still in Cincinnati.  Isabel might be able to get the job done well enough in due time. Don’t misinterpret that, he is not going to come close to a Votto level, but he could be a useful option in the future. He is mostly a power threat who has an ISO of .301 this season. The flip side of that is that he has struck out 42.6 percent of the time this year as well. He isn’t going to be a cornerstone in the future Reds lineup, but he can likely become an occasional bomb guy off the bench.


17. Luken Baker, STL, Age: 22


Baker exploded on the scene in 2018 after the Cardinals made him the 75th overall selection in the draft. It took only eight games to prove he was more advanced than the Rookie-level. He started the 2019 season in Advanced-A ball and it is not going as well. He is slashing .223/.314/.329 this year with five homers. His strength is obvious when you look at his 6’4″ 265-pound frame, but the knock on him even before the draft was his ability to stay healthy. He was in 2018 when he was drafted, and he has been so far this year, but you wonder if there is something ailing him. As his bat matures Baker could become a solid starter at the MLB level.


18. Chad Spanberger, TOR, Age: 23


The Rockies got a solid bat out of the sixth round in 2017 in the form of Spanberger. The Rockies then traded him to the Blue Jays in the Seunghwan Oh trade. In 2018, Spanberger was traded, assigned, reassigned, and when all the dust settled he slashed .298/.355/.538 with 27 homers. This year he is hitting .222 at the Double-A level with nine bombs and a 99 wRC+. It is not surprising that he is struggling a little more at the higher levels of the farm system.  Spanberger needs to adjust like all minor leaguers and find that power swing again. If he can do that, he could be a threat as a  power bat off the bench. He could even become a decent starting option


19. Alfonso Rivas, OAK, Age: 22


When it gets this deep in the first baseman rankings fantasy owners are looking for any hint of future value. That is Rivas. He is two seasons into his professional career and is hitting .284 overall. So far this year he is slashing .283/.389/.413 with a wRC+ of 128. He is not a power bat by any means, but he can hit a little bit. Rivas’ calling card will be his glove as he progresses through the minors. However, if he can continue to make small adjustments to his swing, he can unlock the power to hit 15 homers in a year. It is more likely that he consistently hits between 5 and 10 long balls if given consistent playing time.


20. Pedro Castellanos, BOS, Age: 21


The Red Sox have a decent first base option in Castellanos to put behind Casas in the future. There is not a ton of pop in his bat, but in 287 games he is slashing .306/.351/.345. He puts the ball in play and he gets hits, but he will not drive the ball out of the ballpark on a consistent basis. Castellanos is not a superstar in the making, but he is showing some ability to hit the ball.

Trevor Hooth

Loves watching MiLB and talking about it. Millikin University alum and optimistic Tigers fan.

2 responses to “Post All-Star Prospect Rankings – First Base”

  1. Devin says:

    Can you guys make sure to tag all these articles the same. Seems like different authors tag similar articles (even within the same series) differently and they are hard to find. ie: Catchers list has a dynasty and prospects tag, but this one only has misc tag, Top 100 Prospects only has a prospects tag, etc. Just a suggestion for those of us that like to go back and reference.

  2. Tim says:

    Just curious how this list was created… Nate Lowe was the second ranked 1B in the top 100 hitters list but 6th here? Did I miss this explanation in the catchers article?

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