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2021 in Review: Darwinzon Hernandez is still searching for control

Can Hernandez take the next step and truly become a valuable reliever?

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American League Championship Series Game 5: Houston Astros v. Boston Red Sox Photo by Mary DeCicco/MLB Photos via Getty Images

Welcome to our 2021 Boston Red Sox in Review series. This is, as you can probably guess, where we will be reviewing all of the players who made at least a modest impact on the Red Sox in 2021. Every week day we’ll be deep diving into one player, describing the season in a sentence, looking at the positives from the year as well as negatives, looking back at our one big question from our season preview and looking ahead to the 2022 season. Today we look at Darwinzon Hernandez’s 2021 campaign.

2021 in one sentence

Darwinzon Hernandez showed flashes of brilliance in 2021, but, once again, a lack of control proved to be his Achilles heel.

The Positives

On the surface, Hernandez appears to be an important piece to the Red Sox bullpen. The lefty’s fastball, when utilized properly, is absolutely lethal. His fastball velocity ranked in the 75th percentile, while his spin rate on the pitch was in the 68th percentile. Compared to 2019, Hernandez improved the spin rate on both his fastball and breaking ball, though the velocity for the former did drop. Regardless, velocity and spin place Hernandez above average for the 2021 season.

The southpaw’s fastball was used 70 percent of the time in 2021 and accounted for 40 strikeouts, a .182 BA, a .212 expected batting average, and generated a 31 percent Whiff rate. If Hernandez gets strike one with his fastball, the entire at-bat changes. From there, he’s able to utilize his sweeping slider, the pitch he uses at a 20.6 percent rate, for strikeouts. The expected batting average on Darwinzon’s slider is .222. The fastball, slider combo, mixed in with a 90th percentile curve could prove to be a devastating late-inning combination.

The Negatives

The one true negative for Darwinzon Hernandez has always been the inability to control his pitches. As noted above, Hernandez relies in part on the velocity of his fastball, which he averages about 95 mph. Relievers that rely on velocity often do not have as much control, at least as compared to pitcher that dots the corners of the strike zone. That said, pitchers have certainly been able to improve that part of their game as they have gone along, and Hernandez still does not turn 25 until December. Still, there’s a long way for him to go after walking a whopping 17 percent of opponents in 2021, the second highest rate in baseball among pitchers with at least 40 innings.

Another negative for Hernandez has been an inability to stay healthy. In three big league seasons, Hernandez has logged just 78 23 innings. For 2020, to be fair, it was a positive COVID test that kept him out of action. But beyond that, a sprained AC joint sent him for his second IL stint in 2020, limiting his appearances to just seven games. This year, the southpaw spent time on the injured list in 2021 from July 31 through September 9 with a right oblique sprain. Hernandez’s presence was missed out of the bullpen, given that the only other lefty options were Austin Davis, Josh Taylor, and Martín Pérez, the latter joining the mix after a demotion from the starting rotation.

While Hernandez finished the 2021 season with a 3.38 ERA, his peripherals were worse, finishing with a 4.54 xERA, 4.79 FIP, and a 4.40 xFIP. All of those are down from his 2019 numbers, when his peripherals outperformed his ERA. His walk rate did tick down by a bit less than a percentage point from 2019, but his strikeout rate also fell three percentage points. If Hernandez is to improve his control, the sacrifice associated might be a decrease in his strikeout rate. He needs to continue to get strikeouts, but improving that walk rate is key to unlocking his future potential.

The Big Question

Can Darwinzon Hernandez bring down his walk rate?

Man, oh man, this remains a big question and has been since Hernandez’s debut with the Red Sox in 2019. In 30 13 innings in 2019, Hernandez had a walk rate of 7.71 and in only seven games in 2020 his BB/9 was 8.64. This past season he finished with 31 walks in 40 innings pitched in 2021, still far too high of a rate. If Hernandez is to become a fixture in the Red Sox bullpen he absolutely needs to cut down on walks, as a late-inning reliever cannot afford to be walking a batter per inning. Great teams, heck, even good teams will make a reliever pay for free passes.

2022 and Beyond

It shall be reiterated once again, Darwinzon Hernandez possesses the ability to be a very reliever for the Boston Red Sox. All the tools are there, it is just a matter of whether Hernandez can use the tools to unlock his greatness. Hernandez is arbitration-eligible after the 2022 season and is under control through the 2025 season. It would be in Hernandez’s best interest to have a solid campaign in 2022 not just for the sake of the Red Sox bullpen, but for his own financial gain.

In the immediate future, Adam Ottavino and Hansel Robles are both free agents, meaning that Hernandez might just be given more important innings for the Red Sox in 2022. If Alex Cora decides to give Hernandez more important innings in 2022 he is going to have to earn them, and that begins and ends with proving he can throw strikes. Having an electric arm will only take a pitcher so far. Being a pitcher, rather than a thrower, is more vital to overall career success. If Hernandez can truly lock down his control, the Red Sox have something special, and the sky is truly the limit given the amount of untapped talent in Hernandez’s left arm.