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Diving into the Triston Casas vs. Marcelo Mayer debate

Who has the better case?

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United States v Japan - Baseball Gold Medal Game - Olympics: Day 15 Photo by Steph Chambers/Getty Images

The most important takeaway from the prospect ranking season we are currently in has been the improvement in the top tier of the Boston Red Sox farm system. They’d been building some solid depth for a couple of years now, and that does still continue to improve, but it’s much easier said than done to improve the top portion of the farm. Thanks to a high draft pick last summer, some shrewd drafting in previous years, and good work from the player development staff, Boston has three consensus top 100 prospects and another couple of players who are in that 75-125 range.

That’s most important, but what has been most interesting to me has been the divergence of opinion at the very top between those who cover the organization and those who cover the league as a whole. For the former group, Triston Casas seems to be the guy most have atop their prospect rankings for the organization. However, when you look at the opinions of national writers and evaluators, it seems more common to find Marcelo Mayer atop the list. Ultimately, the difference doesn’t mean much of anything in the grand scheme of things. Everyone agrees both players are excellent prospects and the Red Sox will hold both barring a godfather offer. But I did want to dive a little bit into what makes a top prospect and see what kind of conclusion we come to about ranking these two players.


There’s no denying that the more often a scout is able to get eyes on a player, and the better competition said player is facing in those scenarios, the more accurate scouting information you can be expected to get. Obviously this is largely something that is out of the control of the player, but it’s an important factor here. Talent wins out, but when we’re talking about prospects who are theoretically as close as these two are, this can be something of a tiebreaker. I decided to start with this piece just for an easy layup, because obviously this part goes to Casas, who has been in the organization since 2018 while Mayer has yet to play in his first full season.

Defensive Value

Since we started with a layup for Casas, I figured it was only fair to go next towards the easy advantage for Mayer. We know that a player who is higher up the defensive spectrum (i.e. catcher, shortstop, center field, second base) is going to generally be ranked higher than players who are relegated to the corners, and especially first base like Casas. Mayer is still very young and you never really know how a person is going to fill out as they move up the ladder after being drafted out of high school. It’s possible he will have to move off shortstop at some point. That said, it’s not the expectation. He has the skills, instincts, and athleticism to handle shortstop and most project him to stick there in the majors as well. That provides a decent floor even for such a young player, as you can still provide value if you play a good shortstop even if the bat doesn’t develop as we hope.

Whereas with Casas at first base, you really need to be an above-average bat if you are going to stick at that position, and to start for a contender long-term you need to be significantly better than average. Casas has that potential, but there’s a finer line to walk, even for someone like him who should be a good defensive first baseman. Just looking at position Mayer has an easy advantage in this category.


Scouting in baseball isn’t nearly the same kind of thing we see in football or basketball, where they have highly-publicized combines, and in the case of the NFL fans end up knowing how high a person can jump, or how fast they can sprint a short distance. The kind of athleticism associated with baseball is a different kind and a harder kind to see in plain sight. That said, traditional athleticism does help as well, and especially when you’re projecting a player out. It can provide a higher floor by allowing a player to contribute in other ways, and can sometimes make a scout more comfortable in a player’s ability to stay healthy.

In the case of Casas versus Mayer, it probably goes to the latter in the traditional sense, but maybe not by the margin you’d think. Mayer is a good athlete, though not exactly a burner on the bases. Casas isn’t going to win anybody over with his legs, but he’s a monster of a presence at the plate and has the kind of athleticism and flexibility that a big guy needs to succeed at first base. These two players are built much differently and are athletic in their own ways, but I suppose if you had to pick one you’d probably lean more towards Mayer.

New York Yankees Vs. Boston Red Sox at Fenway Park Photo by John Tlumacki/The Boston Globe via Getty Images


I think sometimes we take the idea of a player’s floor too optimistically, because really every prospect’s floor is that we just never see them in the majors. That’s less the case with Casas now than Mayer just because of the aforementioned experience and proximity to the majors, but it’s still realistically the case. Instead, we should probably think of floor as something like the 20th percentile outcome. We talked above about the defensive value generally creating a higher floor for a shortstop than a first baseman, but things like experience and proximity can shift that calculus a bit. Like with athleticism, this is a place where I think different opinions can coexist. I can see the argument for Mayer because that ability to play shortstop will give him more leeway with the bat. On the other hand, we know that Casas can handle upper level pitching. We don’t know that Mayer can handle A-Ball pitching, never mind Triple-A. Reasonable people can see this one differently, I think.


Just like with the floor, the ceiling is something that we probably look at wrong much of the time as well. In the literal sense of the very best a player can be, there are probably a lot more players with a 70 ceiling on the 20-80 scale than we think, but they just have something like a .5% chance of getting there. That’s not really that useful. So instead, as with the floor, it’s probably more useful to think about their 80th percentile outcome. This is where Mayer really has an advantage, because for the same reason a shortstop theoretically has a higher floor, they also have a higher ceiling. If Mayer’s bat develops to nearly the best that we think it can, we’re talking about a good (maybe not great, but good) defensive shortstop with above-average power and an above-average OBP. For Casas, we’d be talking about a consistent All-Star caliber bat with some seasons in which he appears on MVP ballots, but he has to reach that kind of offense because he gets no leeway with the defense.

There’s also the question of likelihood to reach that ceiling. That is, of course, an impossible thing to project with total confidence, but the job of scouts is to predict the future in that way. It’s hard for me to not pick Casas here because of the experience, but this is really a matter of preference of the type of players one usually leans towards, and how different people weigh different pieces of the same information.

For me personally, I’ve always leaned more towards Casas in this debate, and it largely comes down to the experience piece. For me, when it’s close like this I am pretty much always going to lean towards the guy who is close to the majors and has seen upper level pitching. Nationally, it seems evaluators lean more towards ceiling and are going to give more bonus points for playing up on the defensive spectrum. I think it’s clear that the takeaway here shouldn’t be that somebody is definitively wrong. There is a reasonable path for taking either Casas or Mayer as the top prospect in this organization. It’s just all dependent on a specific person’s scouting priorities.