Written by: James Schiano (@FreePeteAlonso)

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It’s not too noticeable in the win/loss column, but important facets of the Marlins’ future have come a long way this season, mostly due to their fleet of promising young pitchers. Caleb Smith has looked dominant at times (not as much recently), Pablo Lopez has flashed potential, Jordan Yamamoto has had moments, Sandy Alcantara has been brilliant lately. Despite those facts, it was Zac Gallen who seemed to have the highest upside of the bunch. That’s why it was so surprising to see him dealt to the Diamondbacks in exchange for high-risk, high-reward shortstop prospect Jazz Chisholm at the deadline.

The motivation of this trade coupled with the acquisition of Jesus Sanchez from Tampa Bay was clear: Miami wanted to add impact bats to their system by way of their pitching depth. President of baseball operations Michael Hill confirmed the strategy, saying “[the organization] felt like we had a surplus of young pitching, we explored the market to do the best job of maximizing the value of our players.”

Commendable, but accomplishing the mission came at the expense of arguably their most promising pitcher was still puzzling. Nevertheless, both trades were a major vote of confidence in the organization’s pitching depth. Along with those mentioned on the big club, prospects Sixto Sanchez, Edward Cabrera, Braxton Garrett, Trevor Rogers and Nick Neidert have all showed promise in the minors and should continue to ascend prospect rankings heading into 2020.

Left out thus far among most Marlins and prospect circles is right-hander Elieser Hernandez. He is easy to forget about due to his average frame (6’0”, 210 lbs), ordinary fastball velocity (~91 mph) and lack of prospect pedigree (absent from credible Marlins’ prospect lists this preseason) despite being 24-years-old. Yet, his profile hints at the possibility of vast potential. Let’s dive in.

He was acquired from the Astros in the 2017 Rule 5 draft after mild success in their system, but not enough to be added to their stacked 40-man roster. During 11 starts with High-A Buies Creek in 2017, Hernandez compiled a 20.1% K-BB% while pitching to a 3.5 FIP. Hardly elite, but it was a type of foundation that could be built off of.

His first season in the Marlins’ system was forgettable, pitching both in the minors and majors. But rather unexpectedly, he exploded onto the scene this season in Triple-A with the New Orleans Baby Cakes of the PCL. He amassed 48 IP over 9 starts with a 27.4 K-BB% (6th in league among pitchers with at least 40 IP) , 34.3% K% (7th), 15.5 SwSt% (10th), a 2.24 FIP (1st) and astounding 0 HRs allowed (1st). Calling the PCL in 2019 a launching pad is an understatement, which makes Hernandez’s run with New Orleans all the more impressive.

On the surface, Hernandez’s second stint with the Marlins has been nothing to write home about. An unsightly 5.89 FIP, 2.24 HR/9 and low .266 BABIP might appear to leave little reason for optimism, but most underlying metrics suggest Hernandez has been quite unlucky this year. He’s held opposing hitters to an average 85.5 mph exit velocity, better than 94% of qualified pitchers. He’s also underperformed his xBA, xSLG, and xwOBA.

Actual Expected Diff BA .246 .217 .029 SLG .516 .396 .120 wOBA .351 .306 .045

His improvement can be traced to the usage and reinvention of his slider. Like seemingly every other pitcher in baseball has realized, sliders are hard to hit. Groundbreaking. Hernandez has upped his SL% this season to 32% from 22.9% and has seen great results due to its rise in effectiveness.

Hernandez’s slider has a pVal of 7.2 which ranks him 25th out of 346 pitchers who have started an MLB game this season. That value is up from a -1.2 last season. This extreme shift is no surprise given how different the pitch has behaved in 2019.

Eno Sarris wrote a great article a few weeks back trying to determine just what makes a slider ‘good’. Definitely read it for yourself, but he found that there are lots of different factors that can make a slider effective, saying they’re “like fingerprints, every pitcher has their own.” The key, though, is for it to play off one’s fastball in terms of velocity, movement, and spin direction, but there is no exact science (picture below courtesy of The Athletic).

There is cluster of pitches with a desirable RV+ once the difference in velocity is greater than 12 mph and difference in vertical movement is greater than 10 inches, all of which have a separation of spin direction (or spin axis) of greater than 100.0º.

Hernandez’s breaker is being thrown slower, dropping less, cutting more, and spinning far more similarly to his fastball.

SL ‘18 SL ‘19 FB ‘19 MPH 80.3 78.4 90.6 V-Break (+ gravity) -40.3” -33.8” -16.0” H-Break 6.6” 11.1” -7.5” Spin Axis 119.13º 140.59º 205.81º RPMs 2045 2248 2245

While its vertical drop has decreased, the difference remained well above the 10-inch threshold Sarris’s research found for likely effectiveness while being two additional MPHs slower and cutting 5.5 inches further than in 2018. However, Hernandez’s separation of spin axis would be an anomaly: decreasing by more than 20º, having a difference of only about 65º, but still producing better results.

On the other hand, the increased similarity in spin axis along with nearly identical RPMs between the two pitches might have made them more difficult for batters to distinguish as they approach the plate. Sarris talked about the advantage of having your fastball and breaking ball mirror each other with a 180º separation, but the research isn’t quite as sold as pitch designers and analytically-inclined evaluators—yet.

I want to reiterate that Hernandez’s willingness to throw his slider more often is the primary reason for his improvement and why he deserves our attention, but that is due to how nasty the pitch is along with how hard his fastball has been hit.

His fastball has a 60 grade from FanGraphs, which would make the offering plus. In other words, it shouldn’t be a liability. However, Hernandez has developed a tendency to just leave the pitch over the middle of the plate when he falls behind in the count. That’s not the recipe for success.

Whether it’s a desire to limit his walks, purposefully pitching to contact or simply struggling a bit with fastball command, the next step in Hernandez’s development is recapturing the viability of the pitch. The offering certainly plays well up in the zone, but it’s not really getting barreled anywhere other than middle-middle. This feels like an issue that can be remedied rather easily heading into next season. And it’s a necessary fix, seeing as the 24-year-old doesn’t possess premium fastball velocity nor a high spin rate with the pitch.

It’s not rocket science to proclaim that throwing less pitches down the middle will allow Hernandez, or any pitcher, to limit the damage done against them. But often, it takes microscopically small adjustments for pitchers to reach the next stage of their development. There’s no doubt in my mind Hernandez’s potential played—at minimum—a small role in the Marlins’ willingness to move Zac Gallen at this season’s trade deadline. The upside might not be astronomical here, but it is much better than the statistical profile we’ve received from the 138 big league IP sample thus far. There’s potential for back-end, mixed league viability with the 24-year-old, especially as the slider usage (hopefully) continues to increase.

Hernandez’s profile leaves plenty of room for optimism, and he’s someone to keep an eye on over the next month, next season and beyond.

Follow P365 staff writer James Schiano on Twitter! @FreePeteAlonso

Follow us on Twitter! @Prospects365

Tables and graphs courtesy of Baseball Savant, Brooks Baseball and Fangraphs

Featured image courtesy of photographer Dilip Vishwanat and Getty Images