Being Reasonable About Ronald Acuna: He’s Not Trout, Probably

This is a post in two parts. I will first bring you up, and with Atlanta Braves prospect Ronald Acuna the sky’s the limit. There are a lot of stats to show just how great he’s been so far. But be prepared, because I also plan to slam you back down. In the end, the goal is for us to enjoy what Acuna is doing but in the reality that he is still a prospect who could be good to great, but might not be [insert extreme comp here].

Going Up

Ronald Acuna is a man on fire, slashing .338/.403/.619 (184 wRC+) through his first 151 plate appearances in AAA. His blistering hot year has landed him as the top prospect in the organization and a consensus top 10 prospect in the game. Fresh off three home runs in three straight games, fans are clamoring for a call up. That alone speaks to his success considering he’s only 19 and he started the season in high A.

Coming into the season, many prospect watchers were high on Acuna after a dominating performance down the stretch in 2016 for Single A Rome, but his value was suppressed slightly by his limited exposure. Due to an injury, he only accumulated 171 plate appearances in his first year above rookie leagues.

What he’s done this year is impressive. Not only has he moved up quickly from High A to AAA, but he’s improved his performance at each stop despite his Batting Average on Balls in Play (BABiP) dropping at each stop into a more normal range:

WP DataTables

Acuna became a household name in Braves Country when he became the youngest player in AA. His hot start in Mississippi hid a rough patch for much of June, and I covered that more extensively here. However, after the AA All-Star game, he settled in slashing .366/.397/.662 with a 201 wRC+ in 78 plate appearances from June 23^rd to his AAA call up July 13.

What he was doing up to this point was special, but what he’s doing now in AAA is even rarer due to his age. The Fangraphs data base has sortable minor league leaderboards going back to 2006. In that timespan, only three players have more than 50 AAA plate appearances during their age 19 season. Those players: Acuna, Braves second baseman Ozzie Albies (2016), and Nationals outfielder Bryce Harper (2012).

Despite being one of the youngest players in AAA – not just this year but in the last decade – Acuna’s 184 wRC+ is the highest wRC+ of anyone in AAA with at least 100 plate appearances. (Other than Jamie Romak who is 31 and now plays in Japan but put up a 196 wRC+ in 102 PAs earlier this season).

WP DataTables

Comparing Acuna to other young players in AAA, we can see how rare his performance for age is. In fact, it’s so rare, I had to raise the age to include players in their age 20 season to have anything worth considering. Here is how he compares (min. 50 Plate Appearances):

WP DataTables

I have heard a few comparisons to Mike Trout that I dismissed, but I am here to tell you that Ronald Acuna has outperformed Mike Trout in AAA. While Trout’s triple slash is clearly better, weighted Runs Create plus (wRC+) does two things the triple slash does not:

1. It adjusts for park factors. Mike Trout played in the much more hitter-friendly parks of the Pacific Coast League.
2. It compares the hitter’s ability to create runs to league average, where 100 is average and every point above or below is comparable to a percentage better or worse than the league at creating runs.

So while Trout was 79% better at creating runs than other players in his year and league, Acuna so far is 84% better at creating runs in his year and league. In other words, compared to his peers, Acuna has been better. In fact, compared to his peers, he’s been the best player in his age 20 season or younger to come through AAA since at least 2006. That’s a very nice list of players that includes Freddie Freeman, Jay Bruce, Adam Jones, Bryce Harper, Carlos Correa and other current players with very nice resumes.

One final comparison to the regularly comped Andruw Jones:

Two #Braves teenage phenoms with eerily similar swings:

Left: Andruw Jones, age 19
Right: Ronald Acuña, age 19 pic.twitter.com/JupGQnCAhd

— Grant McAuley (@grantmcauley) August 16, 2017

Yes Braves Country, there is a lot to be excited about in Ronald Acuna.

Heading Down

That said, we must use caution in building up his current performance into too high MLB expectations. After all, exceeding expectations as a young player in AAA does not guarantee MLB success.

First of all, we are looking at very small sample sizes to draw very large conclusions. Most of you aren’t stats folks, so let me just tell you now it’s a bad idea to project a player based on the number of AAA plate appearances we are considering. Instead of explaining out why, the coincidences of baseball allow me to easily crush the optimism I’ve built to this point simply by telling you who beat out Trout and everyone else for highest wRC+ in 2012: Brooks Conrad.

Yep, a 32-year-old Conrad was a better hitter than Trout…for 85 plate appearances…in AAA.

Many want to label Acuna as Andruw Jones or Mike Trout, but that is the absolute ceiling if he keeps exceeding expectations, not the likely outcome.

If that didn’t fully deflate your bubble, let’s remember that Trout already had 135 plate appearances in the majors in his age 19 season. And that is another possible hole to consider. Elite players don’t always spend much time in AAA, so we don’t get a great sense of who a player is going to be at that level. Granted, most players are a little older when they attempt this, like Dansby Swanson, who was 22 when he skipped AAA entirely (for better or worse).  However, we do have an example this year to consider, and that’s 20-year-old Raphael Devers of the Boston Red Sox, who recorded only 38 plate appearances in AAA (197 wRC+) before his call up. With the Bo Sox, he’s slashing .348/.416/.667 (180 wRC+) in 77 plate appearances. He didn’t show up in my data due to my (reasonable) inclusion factors, but he makes Acuna slightly less rare.

Perhaps the most important consideration is psychological rather than statistical. We love Acuna. Because of this love for our pure and innocent prospects, not yet stained by MLB pitching under our scrutinizing eyes, we tend to look for information that confirms that opinion of him (also known as confirmation bias). We love to see Freeman on a list with Acuna and are through the roof that Trout is there. Peppered throughout our eyes catch other rising stars and regular all stars.

But the funny thing about confirmation bias is the tendency to minimize information that’s not quite as positive. And there are quite a few names on that list who have struggled in the majors.

A good example is Travis Snider. In 2008, the 20-year-old was a top prospect for the Blue Jays and jumped four levels. After a short but successful start in High A (149 wRC+), he jumped to AA, where he spent most of the season and maintained a respectable 121 wRC+. That earned him a promotion to AAA. In 70 plate appearances there he carried a 146 wRC+. It was a lot of positive progress for a player so young. Enough to get him a cup of coffee in the majors to finish the season, where he again saw success, hitting .301/.338/.446 (110 wRC+) in 80 PAs.

The next year, Snider was the next sure thing, starting the season as the #6 prospect in baseball and the starting LF for the Toronto Blue Jays. But after a hot start in May, he struggled enough to get sent back down to AAA. It was a sign of things to come, as he would struggle at the plate and with injuries for the rest of his career, never putting up a full season of at bats as he went up and down like a Yoyo.

Snider went from a top prospect in 2008 to a free agent in 2015 who had fallen so far he signed a minor league contract from which he was released. He is currently a 29-year-old who managed a .244/.311/.399 (93 wRC+) across 1,971 MLB plate appearances, accumulating 3 WAR across eight seasons, and never accumulating more than 359 plate appearances in a season. He’s now on his third AAA team in three years.

The Reasonable Conclusion

Snider is an extreme example, and not one I expect Acuna to follow, but it’s no more extreme or unlikely than him becoming the next Mike Trout. I’m going to go out on a limb and say he lands somewhere in between. Until we know more, though, I’m going to enjoy the rare performance he’s putting on in the minors and watch as Acuna emerges into whoever Acuna is going to be.