What past Rookies of the Year can teach us about Kyle Lewis, and what we might expect from him in 2021

Whether due to the weight of expectations, the league getting hip to their tricks, natural regression, or a combination of all three, Rookies of the Year tend to slip a bit in their sophomore seasons. Kyle Lewis – last year’s American League Rookie of the Year – certainly hopes to avoid the same fate, but with the schedule adding 100 games from Lewis’ rookie year to his upcoming second year, the peculiar circumstances could make an already difficult transition even tougher.

Between his September callup in 2019 and a “full” COVID season in 2020, Lewis has still only played in 76 MLB games. He’s logged just 317 plate appearances in that time, which is fewer than each of the last five AL Rookies of the Year made in their award-winning seasons alone. But with a healthy start to his MLB career, the Mariners’ center fielder looks to be on track for even more growth and accomplishments. If he can dodge the maladies of past winners and maintain his numbers over 162 games, Lewis will become a rare bird who flies even higher the second time around.

Let’s begin by looking at Lewis’ rookie numbers compared to the last five American League hitters to win Rookie of the Year.

In 2014 José Abreu was the baseball version of BTS, taking America by storm after becoming too powerful in his home country. Abreu led the majors in slugging percentage and OPS+ in his debut campaign, though he did have the luxury of being 27 years old with a run of dominance in Cuba already under his belt.

Aaron Judge was straight up one of the best players in the league during his transcendent rookie season. Judge was the best rookie ever if you don’t count Mike Trout or guys who played before World War I. Like Eddie Murphy, the Yankees’ gargantuan right fielder was a star from the very beginning, raising the entire profile of Major League Baseball like Murphy did for Saturday Night Live.

Shohei Ohtani, who for Mariner fans is the Bart Harley Jarvis of this group, was a much better rookie hitter than I remembered. Even without his pitching stats or the help of any defensive value whatsoever, Ohtani was still worth over two and a half wins. Of the Astros’ recent winners, Lewis’ rookie stats resembled Carlos Correa’s more so than Yordan Álvarez’s. While Álvarez – like Judge two years before him – was the biggest kid on the playground and proceeded to act as such, Correa and Lewis each struggled in certain areas.

Correa’s on-base percentage was the lowest of the bunch due to a single digit walk rate, while Lewis’ slugging percentage was bogged down by a very odd lack of extra base hits. At the end of 2020, K-Lew had 11 homers and 40 singles, but just three doubles and no triples. For a gap-to-gap hitter with as much power as Lewis, doubles shouldn’t be as much of an issue as they were. Especially with Lewis’ BABIP and barrel percentage resting well above league averages, the absence of doubles can probably just be chalked up to wacky luck.

Of course, all of that is in the past. We’re here to focus on what Lewis might do for an encore and what the old Rookie of the Year winners can teach us.

As noted in the table, Álvarez hardly participated in the 2020 season due to a knee injury. He’s now in a similar position as Lewis. Both players will be trying to duplicate their Rookie of the Year levels in 2021, Álvarez is just a year removed from his trophy, though he does have the luxury of more plate appearances and a taste of MLB experience beyond the western divisions. Lewis will be facing a lot of teams, seeing a lot of pitchers, and playing in a lot of stadiums for the very first time.

Each of the other four ROYs stepped to the plate at least 400 times in their sophomore seasons, more than enough for a proper sample. All but Ohtani saw their batting average drop in year two, though both Judge and Correa’s dipped by negligible amounts. Abreu’s first trip around the league was pre-Statcast, but other batted ball data can direct us to some reasons for his slugging percentage, wRC+, and OPS+ dropping so dramatically.

The biggest change came in his home run to fly ball ratio. Part of the explanation for Abreu’s league-leading slugging percentage in 2014 is that over a quarter of the fly balls he hit cleared the fence. Rather than enjoying that same fortune in 2015, his HR/FB fell to 19.7%, much closer to the league average, which typically resides in the 11-14% range.

Photo by Lindsey Wasson/Getty Images

Lewis has also punched above his weight in the HR/FB ratio. A truly impossible 40.0% mark in September 2019 crashed down to the warning track in 2020, but even then, 22 percent of Lewis’ fly balls were going for home runs. Given his average exit velocity (88.3 MPH), which was nearly identical to the league average (88.4), we should not expect Lewis to continue hitting 22 percent of his fly balls over the wall.

With players like Fernando Tatís Jr. and Christian Yelich, both of whom were top three in average exit velocity, their HR/FB’s of 29.3 and 32.4 percent, respectively, make way more sense. Hit the ball hard, it will go far. Lewis was basically saving his big exit velos for home runs, ensuring that they’d both land in the seats and sound very loud. Remember the 104 MPH shot at Dodger Stadium, the 106 MPH blast off Yusmeiro Petit, or the famous 110 mile-per-hour rocket against Justin Verlander?

Statcast has Lewis in the 40^th percentile of exit velocity, which is not likely to dramatically change overnight. The enormous HR/FB ratio assuredly will, though, which means the predictable declines in slugging percentage and wRC+ that have doomed past Rookies of the Year are probably coming too. With more scouting reports on Lewis, we’re likely to see opponents change their approach as well. Lewis killed breaking pitches last season while struggling with fastballs at times. His decreased production down the stretch coincided with seeing a decrease in breaking stuff.

That little blue dot at the end of 2019, when Lewis was raining knives on everyone, shows that he was seeing breaking pitches over 30 percent of the time. Conversely, at the end of 2020, when was much easier to get out, that number was down beneath 20 percent. Here’s his offensive numbers from the tail end of 2019 – when pitchers were still feeding him curveballs – versus the tail end of 2020, when they realized that was a bad idea.

One thing that hampered Judge and Ohtani in their second seasons, and were partially responsible for their reduced slugging percentages, were groundballs. Specifically, hitting way too many of them. As a god-like rookie, Judge wisely looked at his physique and decided hitting the ball skyward would do him well. 2017 Judge had a 34.9% groundball rate and a 43.2% flyball rate. Those numbers basically swapped places in his less productive 2018, when he rocked a 41.7% groundball rate and 35.0% flyball. Same thing for Ohtani, who won Rookie of the Year by launching stuff into the air 32.9% of the time, but regressed the next year as that plummeted to 24.5% and his groundball percentage was north of 49 percent.

Lewis was basically league average in both grounders and fly balls last year. With his sprint speed – which Baseball Savant has in the 76^th percentile of all MLB players – balls on the ground can absolutely become hits. But as we’ve seen with each of the last five AL Rookies of the Year, it’s hard to pack the same punch from year one to year two, and groundballs are not a path to higher slugging percentages. If anything, Lewis may want to try hitting even fewer groundballs, despite enjoying such a good summer while hitting them at a league average clip. The recipe for success calls for heaps of fly balls and line drives, especially if Lewis’ fly balls keep hitting triple digits on the exit velocity gun. He also went to the opposite field more than the average bear, something that would be a welcome tradition and potentially create more of the extra base hits that so strangely alluded him.

Photo by Lindsey Wasson/Getty Images

The elasticity shown by Rookies of the Year between their first and second seasons is well-documented. Sometimes, as in José Abreu’s case, the sophomore slump comes from wildly unsustainable numbers creeping back down to earth. For Shohei Ohtani and Aaron Judge, the launch pads in their bats malfunctioned and started sending everything into the infield dirt.

Kyle Lewis could certainly run into these same problems in 2021. But his encouraging skillset, and a keen plate discipline that we didn’t even mention, should be strong enough foundation to prevent a complete collapse. The amount of breaking pitches he gets, the angle of his bat and subsequent direction of his hits (and how hard those hits go) will likely define the youngster’s season.