Teoscar Hernandez’s path to the major leagues is a story of adjustments. He wasn’t a major prospect coming out of the Dominican Republic, not signing until age 18 and receiving a bonus of only $20,000. He spent four years climbing as far as AA, using his above average power to overcome a strikeout rate that averaged around 25%. He gained some attention from public scouts, ranking as the #9 prospect in a deep Astros system heading into the 2015 season according to Baseball America. That season proved to be a disaster, though, due mostly to an inability to get to his power against high level pitching. He managed only a 75 wRC+. Any prospect shine he’d accumulated faded as the year went on, and that winter he was left off the Astros’ 40-man roster and went un-selected in the rule 5 draft.
That first taste of failure prompted Hernandez’s first major reinvention. He spent the off-season back in his native Dominican Republic working on shortening his swing to improve his contact rate and refining his two strike approach. The tweaks worked, allowing him to slash his strikeout rate to 17% while increasing his walk rate and allowing some of his power to play. He posted a 139 wRC+ in 69 games for the AA Corpus Christie Hooks, then continued his performance with a 128 wRC+ in 38 games with the AAA Fresno Grizzlies, before earning his promotion to the big league club. Although he held his own, managing a 95 wRC+ in 112 PA with Astros, his strikeout rate crept back up to 25% and he was unable to secure a long term job in Houston’s crowded outfield mix.
Back in AAA, he continued to hit to start the 2017 season, but there was no clear path to sustained big league playing time. That August, Hernandez was traded, along with fellow surplus outfielder Nori Aoki, to the Blue Jays in exchange for Francisco Liriano. Seizing the opportunity with his new club, Hernandez underwent his second reinvention down the stretch that season. He amped up his aggressiveness, going from a patient 42% swing rate with Houston to just over 50% in Toronto, and he started swinging really, really hard. His strikeout rate jumped to 37%, his highest at any level where he spent more than 10 games, but his isolated power also surged to .341, a career high by far. His 134 wRC+ was a ray of hope in an otherwise grim end to the season for Jays fans.
The new approach continued through the 2018 and 2019 seasons, but with diminishing returns. Hernandez’s power (48 home runs in 259 games across those two years) made up for strikeout rates in the low 30% range, keeping him a slightly above average hitter. That was enough compensate for outfield defense that ranged from questionable to baffling and hold down a starting job with a rebuilding club, but not to secure a definite long term role on the next good Jays team.
2020 brought a third major change, this one more an evolution than a reinvention. Hernandez went from hitting the ball very hard, with average exit velocities between 91 and 92mph, to absolutely crushing it, pushing his average to 93.3mph, fifth among all hitters who put at least 100 balls in play that season. He continued to strike out more than 30% of the time, and to walk at a below average clip, but with power like that it simply didn’t matter. He smashed line drives all over the park (and huge home runs out of it), and his 143 wRC+ lead the Jays back to the playoffs for the first time in four years.
Coming into the 2021 season, Hernandez seemed to have found his long term identity as an MLB player. When on, his huge power could anchor a playoff calibre lineup, but his poor contact skills and sometimes dicey plate discipline made his profile a risky one. 2020 showed what that skill set could look like at its best, but 2018 and 2019 showed that just a little regression in his quality of contact might reduce him to a fringe starter. The first 7 games of the season reinforced that downside, as Hernandez struck out 14 times in 29 PA while not walking once and managing only a 38 wRC+. Then he tested positive for COVID-19 and spent 3 weeks quarantining and recovering.
Somehow, during that down time, Hernandez seems to have gone through yet another reinvention. In 124 PA from his return through Sunday night, Hernandez has trimmed his strikeout rate down to 17.7%, 13 percentage points between his career rate. May represented the lowest strikeout rate in any month of his career and his first time below 21%. He’s whiffed on only 25.6% of his swings, the first time in his entire career he’s been below 31% for a month. Somehow, he’s managed that without sacrificing anything in terms of his power on contact, with a 92.8mph average exit velocity and 50.6% hard hit rate that are right in line with what he managed last year. A rough series against an excellent Marlins rotation puts a dent in these numbers, raising his strikeout rate since his return from COVID to 20.3%, but that’s still the best sustained stretch of contact in his MLB career by a fair amount.
To try to figure out what’s changed to allow this apparent breakout, I’ve broken down his stats by year (starting 2021 with his return from the COVID IL). The first set of graphs below shows his contact rate in different regions of the strike-zone (all graphs are from the catcher’s perspective). His best zone has always been down and in, with contact rates in the high-80s since 2018. League-wide contact rate inside the zone was 85% in 2018, and has slid to around 83% this season, so Hernandez has always been average or a little better on swings down and in. Starting in 2020, he improved further, raising his contact rate in those areas to the high 80s or low 90s percent. On the flip side, he used to have a major hole in his swing up and away, missing those pitches nearly half the time in 2018 and 2019. He started to close that hole in 2020, and in 2021 he’s gotten his contact rate above 70% in all but one sector of the strike zone. He’s managed to shore up his biggest weakness at the same time as he’s consolidated his major strength, becoming a better contact hitter all over the inside of the strike zone.
The next set of graphs shows his swing rate across various parts of the strike zone. In 2018 and 2019, he swung most often at pitches over the heart of the plate, but was pretty aggressive all over the zone. League average swing rate inside the zone varies between 65 and 66%, so in 2018 Hernandez was more aggressive than average in 7 of the nine areas inside the zone and in 2019 he was more aggressive in all of them. In 2020, though, he clearly shifted his focus to pitches in, and especially up and in. He swung less than average in 6 of the 9 areas of the zone, and especially laid off pitches on the top and bottom corners away. He’s continued that trend in 2021, getting a little more aggressive overall but still clearly focusing on pitches in at the expense of ones away. This change in approach has come with a cost, as he’s started chasing a bit more on pitches up and in, but it allows him to stay away from what’s still an area of relative weakness away while being aggressive on balls he can reliably get to.
Finally, the third set of graphs shows expected wOBA for balls in play based on exit velocity and launch angle. Essentially, this shows where Hernandez does damage when he does swing and make contact. You can see that Hernandez just made much better contact in 2020 than the did in 2018 and 2019, and that the improvement is mostly sustained in 2021. In the first two years, his best zones were middle in and middle-middle respectively, with xwOBAs of about .630 on balls in those areas that he put into play. In each of 2020 and 2021 he had several zones with xwOBAs above .700. He appears to actually do the most damage up and away, the same place he’s previously had trouble making contact. That might just show that he can only catch up to mistakes up there, but that when he does he can extend his arms and really crush them. Samples are fairly small in a lot of these areas, though, especially in partial or abbreviated seasons. The only thing that can be reliably be concluded is that Hernandez’s quality of contact is reliably better than league average (about .360) in all areas of the zone except down and away, and that it’s significantly improved between 2019 and 2020 and that improvement has been maintained in 2021.
It remains to be seen how much of this can be sustained. Contact rates become reliable extremely quickly, though, and 124 PA is enough that an apparent change this large is extremely unlikely to be nothing but luck. I wrote a similar piece about Rowdy Tellez after upped his contact rate and slashed his strikeouts in a 127 PA sample last year, and while a lot else has gone wrong for Rowdy at the plate in 2021, he’s still making better than average contact and his strikeout rate has only regressed about a third of the way back to its previous level. If Teoscar Hernandez can manage to keep any significant fraction of this improvement going and cut his true talent strikeout rate from his previous low 30s level to the 25% range he mostly occupied in the minors, and can continue to combine that with his 2020 exit velocity gains, he will be one of the most dangerous hitters in baseball.