Can Deyvison De Los Santos overcome these approach concerns?

First, I would like to highlight how hard Deyvison De Los Santos hits the ball. He has posted a max exit velocity of 119 mph, putting him in the company of MLB's elite power hitters like Ohtani, Judge, and Stanton. This is especially impressive coming from a 21-year-old.

De Los Santos has made a name for himself in the baseball world by leading all of Minor League Baseball in home runs. Many Marlins fans were understandably excited to add somebody like this to their minor league system. Although his potential is through the roof, there are some major concerns to highlight when it comes to plate approach.

De Los Santos had 12 home runs with Triple-A Jacksonville after joining the Marlins org in late July, and 40 on the year between AA and AAA. It feels as if many people can be blinded by his immense power and miss out on a critical question: If he isn't hitting home runs, what can he do?

De Los Santos does not walk. He had a 5% walk rate following the trade, which tied into his poor .284 OBP. His chase and whiff rates are even more concerning.

This graphic shows De Los Santos' whiff rates per zone from August and September. The right-handed batter has a massive hole up and inside. He also swings and misses a ton out of the zone. This swing-happy approach has hurt his production greatly. In the final 30 games of the season, De Los Santos chased at a 51% rate. For context, league average is a 28% chase rate. When you combine bad whiff and chase rates, you get too many strikeouts.

De Los Santos only had a 28% strikeout rate as a Marlins prospect. That seems manageable on the surface with the help of an above-league-average 57% out-of-zone contact rate. However, I believe if he were to play in the major leagues right now, he'd easily have strikeout rates over 35%. Teams scout opposing players more thoroughly in the majors and would know that they have no reason to throw him anything near the zone, the same way Javier Báez is treated. 

Because De Los Santos has been making hard contact in all quadrants of the zone, he has adopted an aggressive mindset, leading to quick plate appearances that keep his strikeout rate down. This may work in the minor leagues, but a jump in quality of stuff and scouting would certainly hinder his ability to maintain this.

When De Los Santos isn't hitting the ball over the fence, he's usually putting it on the ground. This season, he posted a 53 GB% with Jacksonville. This is due to swinging at everything, even offspeed and breaking pitches that dip below the zone.

As the season went on, De Los Santos saw fewer fastballs and more secondary stuff. He saw less and less pitches in the zone, but continued to try to hit them. 

It's not all doom and gloom, though. De Los Santos is only 21 years old and the Marlins can afford to be patient. They are clearly committed to the young slugger with hopes of developing his eye and patience. Skill and talent is not the issue—he has real 50 home run potential. If De Los Santos simply swung and missed at an above-league-average rate, he'd be the best power hitter the Marlins have had since Stanton.

My fear is that if De Los Santos does not fix his approach, he has no value as a player outside of hitting home runs. He is going to be a 1B/DH, which gives him nearly no margin for error in terms of his development.

De Los Santos is the epitome of a boom-or-bust prospect. His "boom" is really loud and his "bust" is strikingly low.

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