Atlanta Braves Winning the Atlanta Braves a Championship: Ronald Acuna vs Christian Yelich By

The MLB rumor du jour last week was that the Atlanta Braves were interested in both of the Miami Marlins’ remaining stars, Christian Yelich and JT Realmuto. The baseball blog world immediately concocted potential trades. Some made sense for both teams, while others seemed to pretend the Marlins would accept a bag of Frito’s for their young stars.

I ran through my rolodex of the Braves minor league system and decided that a deal for both players would be fun and reasonable. The Braves strategy for the last few years has been to stockpile pitching prospects for just such a trade. From my 2015 analysis of the Andrelton Simmons trade: “Young pitching is the currency in baseball that money can’t buy.” Since the Marlins don’t have any money, that quote seems to hold up well.

I then thought about a potential Yelich trade from the Marlins’ perspective and realized that they would probably want something of a replacement for their outfielder. The Braves happen to have a star outfield prospect named Ronald Acuna, who might be baseball’s top prospect this spring. So I ran a poll:

I was really surprised by the results. The only two people who really matter (Braves GM Alex Antholopolous and Marlins executive Derek Jeter) probably didn’t vote in the poll, but 92% of the respondents presumably value Ronald Acuna over Christian Yelich.

This comparison might not be the perfect accounting of Acuna’s value in the baseball world- its hard to tell how informed the Twitterverse is about Yelich, but let’s go over the implication.

Yelich is under team control for the next 4 years for a total of $44.5M with an option that could extend the total deal to 5 years for $58.25M. He’s also a 26-year-old outfielder with both a silver slugger award and a Gold Glove on his resume. He’s averaged 4 bWAR over the last 4 years, never posting a figure lower than 3.5, and there’s no reason to anticipate he will slow down soon.

He’s an all-around contributor: a gold glove left fielder, who hits for a high average, pops about 20 homers per year, and steals about 20 bags per year. He’s also well established at the big league level.

Ronald Acuna, meanwhile, just turned 20 years old. He has the potential to contribute in every part of the game. His 2017 minor league season was incredible – he stole 40 bases, knocked 21 homers, and managed to hit for a .325 average while competing as a 19 year old against players significantly older than him. The sky is the limit in terms of who Ronald Acuna ultimately becomes, but the reality is that he’s a prospect.

These guys don’t always work out. Remember Jurickson Profar? Sure, he’s an extreme recent example of a failed prospect. But consider Wil Myers. As a prospect, Myers was universally ranked among the best in the game as a 21-year-old. He won rookie of the year and is now the face of the Padres. Myers has worked out pretty well, and has still only been worth 1.5 WAR per season through his first 5 years. He’s been exactly league average in terms of baseball-reference’s wins above average (WAA) stat.

We know prospects don’t work out. I’m not breaking any news here. I’m merely emphasizing that Acuna would really have to work out in order to be better than Yelich over the course of their contractual control periods. Acuna would have to immediately become one of the best 30 or so players in baseball, and stay there for the next 6 years. It’s certainly possible, but I’m not sure it’s the most likely scenario.

Just like my poll respondents, I don’t think I do that trade as the Braves either. But it’s not because I value Acuna over Yelich. If given my choice and a blank slate, I think I pick the certainty of Yelich over the potential of Acuna and I don’t allow myself to ever think about it again.

However, the trade would not happen in a bubble; the Braves have to consider the rest of their roster. Yelich would join a team that’s still a year or two from competing. The pitching prospects need more time in the oven before they’re ready. This changes the trade calculus. We’re comparing 4 years of Yelich in the contender window against 6 years of Acuna in the contender window. Put another way: Yelich is certainly preferable to Acuna in 2018, but does that really help the Braves?

FiveThirtyEight’s win pay curves can be used to think about this. According to authors Mike Lopez and Noah Davis, the incremental value of each win is highest in the 90-win territory. Their fancy math boils down to a simple thesis: The incremental value of 90 wins, rather than 86, is huge. The incremental value of 76 wins, rather than 72 is… not as important.

If the overall goal is more wins across the next 5 years, then Yelich is probably preferable to Acuna. If the overall goal is a championship, Acuna’s championship value added outweighs Yelich’s. Acuna’s potential factors into that championship value added, but it’s the concurrent window of competition for the rest of the organization that make Acuna preferable to Yelich for the Braves.

-Sean Morash