The evolution of Ronald Acuña into a superstar prospect

Prior to last season Ronald Acuña was a young, raw, high-upside lottery ticket of a prospect. He was a kid that Braves fans knew well, while the rest of the baseball wasn’t very familiar with him. That’s not all too different from a guy like Isranel Wilson today - note the comparison is simply in how they’d be generally categorized rather than a comparison of their games or calling Wilson the next Acuña.

In that last year and a half since the beginning of the 2016 season, little outside of a broken hand has been able to slow Acuña down, whether it was at any level in the minor leagues or playing winter ball in Austrailia. Acuña has emerged from that lottery ticket into a potential superstar and one of the best prospects in the game despite still being a teenager.

Why is that you may ask? Well there are a few reasons why Acuña has become the potential superstar, as we’ve seen incredible growth in a few areas of his game that explain it.

I’ve seen plenty of Acuña and am using a combination of in person evaluation along with television and stats. Last year my viewing of him was limited to MILB.tv. This year I was able to see him live in Lehigh Valley, Syracuse, and most recently when he hit three homers in three days against Scranton/Wilkes-Barre while he played for Gwinnett. Prior to that MILB.tv was used while he was in Double A. My background on Acuña’s time with the Florida Fire Frogs is limited to mostly statline scouting and the videos/highlights posted online.

There are two main factors with Acuña that I’ve found to have contributed in his growth as a prospect. Those two areas are: type of contact and his plate discipline. These two factors, along with the normal growth of a player his age(adding strength) are what has Acuña knocking on the door in Atlanta.

Type of Contact

One notable thing about Ronald Acuña during the 2016 season is that he was an extremely high volume ground ball hitter. According to MLB Farm in his 171 plate appearances in Rome, he hit a ground ball 62.8% of the time. For those who don’t look into these stats, thats’s a very high mark and one that is the exact opposite of what you would see from a power hitter.

This year Acuña is hitting a significantly lower percentage of ground balls. He’s still hit the most grounders out of any type of batted ball, but he’s hit significantly less. He’s hit 41.3% of his batted balls as grounders.

That’s a 21.5% decrease in ground balls, which is absolutely huge for him. It means more hard hit balls. If you wonder why he has so many more extra base hits this year in addition to having a healthy thumb, it’s because grounders equal singles at best for any hitter.

One of the better ground ball hitters in the big leagues is Jose Altuve, who isn’t a similar player to Acuña but does have some similarities to Acuña in 2017 batted ball profile. This year Altuve has a 46.2% rate of ground balls, not all that different from Acuña. While he has an average of .354 on those 206 ground balls per FanGraphs, he has just eight doubles as his only extra base hits on those ground balls.

Instead of those ground balls Acuña is hitting more line drives, the mark of a hard hit ball. Last year he had just 16.4% of his batted balls go for line drives. He’s at 24.5% this year, or a nearly 50% increase in the total. For comparison Altuve has just 89 line drives this year for a 20.2%. However Altuve has 14 doubles and a triple on a ridiculous .753 batting average those 89 liners(67-89), as those hard hit balls are tough to field.

Acuña is also hitting more fly balls, and more fly balls equals more home runs. He hit 16.4% of his batted balls as fly balls last year, the same percentage of his 2016 line drives. This year the number is 29.6%. His homers per fly ball aren’t terribly different from 2016 to 2017, but he’s just nearly doubled up on the number of fly balls he’s hit and explains why he’s been hitting so many more homers. Altuve has a fairly similar 33.6% fly ball rate this year and has 14 doubles, three triples, and 21 homers on 150 fly balls.

It’s not like Acuña has suddenly added power. This is a kid who impressed in spring training of 2016 for his power potential. Instead Acuña has figured out how to do a better job of hitting the ball harder in game. Part of that is his improvement with age, but the other part is the next point.

Plate Discipline

Ronald Acuna has become a much more patient hitter this year. That’s a big part of why he’s able to hit more line drives and fly balls, as he’s not chasing as many bad pitches and he’s getting himself in hitters counts. During the dominant series in Scranton that I watched, he did occasionally swing early in the at bat but was also sitting back and working the count. He’d get ahead in the count and then get a good pitch, and to no one’s surprise he would punish the ball for extra bases.

As you see in the table, Acuna was able to drop his strikeout rate at every level he increased this season. That’s almost unheard of, especially for a 19 year old who is facing Double A and Triple A pitching. He’s also seen a jump in his walk rate since leaving Florida- and actually until the last two weeks of the season his Gwinnett walk rate was better than his Mississippi walk rate.