One Big Question: Can Darwinzon Hernandez bring down his walk rate?

Welcome to the annual Over The Monster One Big Question season preview series. Over the next 40(ish) days, we will be running through every player on the 40-man roster and identifying a key question for them pertaining to the coming season. This should run us up to the start of the season, at least as it is scheduled now. We will go through the roster in alphabetical order. For the most part, these will run Monday through Friday every week running up to the week before Opening Day, though expect some weekend posts mixed in as well as the 40-man is expected to continue to be altered before the start of the season. You can catch up with every post by following this link. Today we take a look at Darwinzon Hernandez.

The Question: Can Darwinzon Hernández bring down his walk rate?

The Red Sox have made some upgrades to their bullpen this offseason, specifically adding Hirokazu Sawamura, Adam Ottavino and Matt Andriese. But as much as they’ve brought in new hurlers, the Red Sox are still going to lean on some familiar faces this year. Darwinzon Hernandez is one of those returning contributors and this might be the year where he takes on an even more prominent role.

Up to this point, Hernandez has been used relatively sparingly, logging 38 ²⁄₃ innings over his first two seasons at the MLB level. He’s racked up those frames primarily as a reliever despite being a starter for most of his time in the minors. That doesn’t really matter now, as its clear that his best shot at a full-time gig in Boston is through the bullpen. He will likely be given every chance to maintain such a role, especially since he is one of only a couple left-handed relievers on the roster. However, to really cement himself as contributor for years to come, Hernandez has to work on his control and drastically reduce his walk rate.

This has been a problem throughout Hernandez’s professional career and not one borne out of facing the top competition available the last two seasons. As he rose from Rookie Ball to Triple-A between 2014 and 2019, Hernandez’s walk rate has gone as high as 20.8 percent and never fallen below 10 percent. So when he was promoted to the majors in 2019 and produced a 17.7 percent walk rate across 30 ¹⁄₃ innings, nobody could pretend to be shocked. What’s interesting, though, is that despite allowing free passes so frequently, Hernández was still good in 2019, especially if you rely on more advanced metrics. For example, he produced a FIP of 2.75 and an ERA+ of 109, indicating that he was an above average reliever that season by results, and well above-average by the peripherals.

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In the shortened 2020 season, Hernandez got much less work, partially due to COVID and partially due to injury, but he was very effective in the rare moments he was on the field. Across seven appearances (8 ¹⁄₃ innings), he posted a 2.16 ERA and a 32.5 percent strikeout rate. While his strikeout rate fell from his mark in 2019 (38.8 percent), he was still far above league-average territory. What’s more, Hernandez’s luck turned around quite a bit, as his batting average on balls in play fell from an astronomical .433 in 2019 to a palatable .278 in 2020. Now, as we’ve had to write in just about very post over the last year, the 2020 season provides a pretty small sample, especially for relievers, so there isn’t as much instructive material to take from Hernandez’s stat line. However, right next to all those positive numbers I’ve just mentioned, as influenced as they are by the small sample, is yet another troubling mark in walk rate, which sat at 20 percent. So while we have to take a sizable grain of salt with most of Hernandez’s 2020 production, it’s tough to think that the inflated walk numbers are just a symptom of a small sample.

One thing Hernandez could do to really progress in this area is to get ahead in the count more often. He showed some flashes of such an improvement last year, as he threw first-pitch strikes 67.5 percent of the time, which was quite a jump from the meager 40.8 percent mark he put forth in 2019. Interestingly, even though he has historically dug himself a hole to start at-bats, Hernandez does hit the zone at a roughly league average rate, but that’s clearly not doing enough.

There’s also a bit of a discrepancy in where he misses depending on the batter. Based on 2019 data, his walk rate is highest when trying to get lefties to chase away or low and inside. On the right side, it has usually been an issue with leaving the ball up, although he’s also shown a tendency to miss when trying to go inside to jam right-handed batters. Unfortunately, while missing in those zones has been to blame for a lot of walks, some of those areas are where he has some of his highest strikeout percentages, particularly up in the zone. This makes for a constant balancing of risk versus reward. Last year, Hernandez came down on the reward side more often, but there’s no guarantee that will continue.

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On the bright side, Hernandez’s actual offerings are relatively solid, especially when it comes to velocity and spin. In 2019, he ranked in the 84th percentile in fastball velocity, while his fastball spin rate (70th percentile) and curveball spin rate (64th percentile) were each above average. Unfortunately, Hernandez doesn’t throw is curve very often and when he does, it’s against righties. In fact, all nine total curveballs he’s thrown at the MLB level have been to righties. The breaking pitch Hernández uses most often is his slider, which breaks away to lefties, often entering the same zone where he tends to give up walks. Perhaps the fix to Hernandez’s walk rate issue is to tighten up his slider so that it snaps over the outside corner, at least from time to time, rather than consistently sweeping out of the zone.

Regardless if that’s the solution or not, Hernandez is probably still going to walk a higher percentage of batters than average. To begin with, relievers tend to have higher walk rates than starters. In addition, Hernandez generally relies more on velocity and stuff than on painting the corners. That’s why his strikeout rates have been so high, but it’s why his walk rates get up there as well. Obviously the Red Sox don’t want Hernandez to stop striking guys out, so the real answer here is to find the right balance between trying to get batters to chase and hitting the strike zone more frequently.

Hernandez can definitely do the first part and the Red Sox can probably live with him falling short on the other. However, if he can limit the free passes just a little without giving up his strikeout production, Hernandez will be that much more effective, which is something the Red Sox need as they try to rebuild a bullpen that failed more often than it succeeded in 2020.