Highlights, concerns from Sixto Sánchez’s MLB debut

In a year where the word “unprecedented” is being thrown around like a baseball on the diamond, teams across the Major Leagues have been calling up their high-level prospects as frequently as ever. The Marlins have been no different, debuting nine of the organization’s top 30 prospects, including top pitching prospects Sixto Sánchez and Trevor Rogers.

As the top prospect in a loaded Marlins farm system, Sánchez’s big league debut was one of the more anticipated of recent memory. The flame-throwing right-hander who was the centerpiece of the J.T. Realmuto trade has long been seen as an integral part of the future of the Marlins rotation. Last Saturday, Sánchez showed the baseball world why the Marlins were willing to part with the top catcher in baseball for him when he picked up his first career win against the Washington Nationals by surrendering three runs across five innings and striking out four.

Sánchez’s fastball appeared as advertised, averaging 98.5 MPH with five of his first eight pitches hitting triple digits. As expected, the changeup was his best out pitch and the slider was no slouch either. Sixto did a good job of mixing up his advanced arsenal, throwing 35% fastballs, while going to the change and slider 25% of the time each. The right-hander also mixed in a handful of sinkers and a couple curves to remind the Nationals hitters that he has quite a few pitches he can go to.

Throwing strikes wasn’t an issue for Sánchez as he did not walk a single batter and hurled 46 strikes against 20 balls. With a 4.8 BB% in his minor league career, control was never a concern for Sixto, but his command was one of the areas that was lacking in last Saturday’s start.

For reference, having control is more or less just throwing strikes, but having command is when the pitcher is able to manipulate his pitches to move the way he wants them to while hitting the targeted spots within the strike zone. For Sixto, his fastball command lagged behind his secondary pitches.

All three of the runs that Sixto surrendered came on two swings, a solo home run from Yan Gomes and a two-run blast by Victor Robles. Both home runs came on his heater and both pitches missed their spot.

Many rave about the movement that Sixto’s fastball possesses, a tailing/sinking action away from left-handed hitters. The struggle for him is getting hitters to swing and miss at that fastball. It almost seems counter-intuitive—how could triple digits with movement be easier to hit?

Sixto’s secondary stuff plays best in the bottom part of the zone, as all changeups, sinkers and most sliders do. The challenge for him is that his fastball also is most effective in the lower half of the zone due to the tailing and sinking action it possesses. You pair the natural tail back over the plate to right-handed hitters with the struggles to hit his spots and the result to Gomes and Robles, the 8 and 9 hitters in that ballgame is easier to understand.

This isn’t anything new for Sixto, so we aren’t just drawing a conclusion from one outing. As FanGraphs points out, the right handed pitcher has struggled to consistently miss bats with the fastball at the minor league level with a 8% swinging strike rate on the pitch (MLB Average is 11%).

With seemingly Sixto’s entire arsenal playing better in the lower third of the zone, hitters are able to look for a spot. Anything that starts at the knees, a hitter can shut it down assuming it will likely drop out of the zone, while anything elevated a hitter can feel more confident in his ability to catch up to the pitch, especially a right handed hitter.

When you take a look at the batted balls by zone for righties, you can see that hitters a hunting fastballs that start inside and tail back over the middle, or start belt high and tail to the lower part of the zone. Having an idea of where the pitch will end up makes things easier for the hitter for obvious reasons, especially when the fastball and changeup have similar movement and sometimes limited separation in velocity.

Sánchez was much more effective against left-handed hitters, which was to be expected with the changeup, but came as a bit of a surprise with his slider. Typically a hard slider would be tougher for right handed hitters to hit from a right handed pitcher, but Sixto had more success using it to backdoor lefties or bury it on their back leg.

While the whiff numbers against left-handed hitters is encouraging, the inability to command the upper third of the zone is consistent. Fortunately, his changeup is nasty enough to lefties to help him keep hitters off balance.

Still, Sixto’s sinking action on his pitches can be useful. As you may expect, he gets a lot of ground balls, hovering around 55% in his minor league career (MLB average is 44%). His start against the Nationals was no different, as he induced 10 ground balls out of the 19 balls put in play.

Don’t be mistaken, Sixto Sánchez has all of the tools to be an ace at the highest level, but that has been known for a while. Even as Sánchez stands now, he will still be able to help this Marlins team in the immediate future with his ability to throw strikes and get ground balls.

Still, the focus should be how he can reach the lofty ceiling that has been set for him by so many scouts, evaluators, front offices and fans. A big step in that progression will be improved command of the fastball and maybe even adding a more traditional four-seamer that will be more effective in the upper part of the zone.

When it comes to sheer tools, Sixto Sánchez isn’t a pitcher you come across very often. Time will tell if he can maximize the gifts he has.