Shin-Soo Choo Is Turning Back the Clock

After the 2017 season, Shin-Soo Choo’s contract looked like one of the worst in baseball. He’d just wrapped up the fourth season in his seven-year, $130 million deal with Texas, and had failed to top 1.0 WAR for the third time. He was well into his mid-30s, had no business playing the outfield, and was constantly battling through injuries. His bat needed to thrive in order for him to be playable in Texas’ lineup, and too often, it was merely average. With three years and $62 million still owed to him, the Rangers needed Choo needed to take a dramatic step forward at the plate. What were the odds of that?

Higher than you might have thought. In 2018, Choo’s wRC+ rose from 104 to 118. This year, at 37 years old, it’s up to 124. That may be just a small improvement from last season, but it doesn’t convey how much he has changed as a hitter. He’s raised his ISO and slugging percentage 40 and 56 points respectively. Choo has sacrificed a bit of his famously high walk rate to get there, but he’s still drawing a free pass more than 10% of the time. What stands out to me, however, is how hard he’s hitting the ball.

Before last year, Choo had never finished a full season with a hard-hit percentage of at least 40%, according to our own data. Then, in 2018, he got that mark up to 42%. This year, it’s up to 46.7%. That kind of gain would be encouraging for a player of any age, but for a player as old as Choo, it’s a significant shift. His hard-hit rate ranks 18th in baseball this season, and that’s only if you go by our metrics. Statcast has his hard-hit percentage at 50.7%, which places him seventh among hitters with at least 100 batted balls. Here’s the full top 10, with ages attached:

Five of the top six are mid-20s sluggers, as are Nos. 9 and 10. Donaldson and Cruz are the only other guys on this list who are in their 30s, but those two have been premier power hitters for a long time.

Now, a player hitting the ball harder than he ever has in 2019 isn’t necessarily a big deal. Many players are doing that. The league-wide hard-hit percentage of 38% is higher than ever, besting the previous record set last year by 2.7% and all other years on record by at least 6%. And Choo isn’t some career Quad-A utility bat who has never been a serious weapon before. He’s accrued 35.6 WAR and posted a 125 wRC+ in his career. He’s always been a great hitter. He’s just doing it differently now.

His age, however, does make this bump in hard contact notable. In the 18 seasons for which we have batted ball data on this site, 30 players age-35 and older have finished a season with at least 400 plate appearances and a hard-hit percentage of at least 40%. Here’s where Choo stands on that list:

Nelson Cruz leads the majors this season, and there’s a separate article to be written about his performance in his age-38 season. Again, though, he is someone you expect to get the most out of each swing. Most other hitters on the list have similar reputations — Barry Bonds, Jim Thome and David Ortiz are some of the greatest sluggers of all time. Meanwhile, Choo has 207 career homers, and a career slugging percentage of .450. He’s certainly been a good hitter throughout his career, but he seems out of place at the top of this list.

The specifics of his hard contact are also worth mentioning. Many players who have unlocked additional power in recent years have done so by elevating the ball more, but that isn’t the case here. At 27%, Choo’s fly ball rate is quite low — nearly eight points below league average, and three points under his own career average. He also hasn’t increased his line drive rate, nor has he pulled the ball more often. Choo’s batted ball profile looks quite similar to his historical norms; he’s just squaring up more pitches than ever before.

Since he became a full-time player, Choo has been one of the best fastball hitters in the game. Going back to 2008, only Joey Votto has generated more total value against fastballs than Choo, according to our wFB rankings. That trend has continued well into the late stages of his career, as he’s posted wOBAs of .400 or better against fastballs in four of the last five seasons (it was .385 in 2017).

It’s the other pitches that have typically given Choo problems. By our weighted pitch metrics, he’s been below average against curveballs and sliders for his career, and just slightly above average against changeups. Between 2015 and 2018, Choo produced a range of wOBAs from .206-.252 against breaking balls, and xwOBAs from .235-.280. He’s built a very impressive career at the plate, but has done the vast majority of damage against fastballs. This year, that’s no longer the case.

It’s immediately clear where the boost to Choo’s hard contact is coming from. While remaining the great fastball hitter he’s always been, he has started hammering breaking balls too. In just one year, he’s raised his wOBA against breaking pitches by 58 points, his xwOBA by 102 points, and his exit velocity by 6.5 mph. It isn’t just his performance against one pitch that’s carrying the numbers here, either: his improvements are evident across the board. His xwOBA against sliders is up from .224 in 2018 to .324 this season, and from .271 to .371 on curveballs. In both cases, we’re seeing dramatic increases in hard contact without any corresponding increase in whiffs.

One would expect this development to be the result of a conscious decision. According to Choo, however, there has been no such effort to make himself a different kind of hitter. From a story by Stefan Stevenson in the Fort Worth Star-Telegram:

I don’t really change. They’re pitching me the same,” he said. “I’m not more focused. I’m not really a home run hitter. I want to just get on base, see a lot of pitches. That’s it. Show a good example to the young players. That’s my job. I’m not trying to hit homers. Just have a good at-bat.

Far be it for me to call Choo’s words into question, but there is some evidence to the contrary. For starters, he is being pitched slightly differently — the percentage of fastballs he’s seen this season is down six points from his career average, and more than five points from just last year. Pitchers league-wide are throwing fewer fastballs than ever before, so it makes sense that they’re doubling down on that strategy against one of the game’s elite fastball hitters.

Choo’s mechanics at the plate are also a little different this year. Here’s a clip of Choo striking out against an Adam Warren slider last September. Pay attention to his front leg throughout the swing process.

Now, here’s a clip of him homering against an Anthony Swarzak this April.

There’s a small, but notable contrast there. He’s not fidgeting as much, and he has a much more pronounced lift with his plant leg as he goes into his swing. In watching clips of him over the past two seasons, this difference keeps coming up. Here’s Choo swinging through a Ryan Yarbrough curveball last year:

And here he is attacking a Tanner Roark curve this year:

That leg kick could be helping Choo better stabilize his swing for breaking pitches, or could simply help with his timing. It also might have little to do with his recent success. But whether it’s the new mechanics, a friendly hitting environment, or a matter of sample size, Choo is barreling up pitches with impressive regularity, despite being 15 years into his career and never hitting the ball this hard before. If he can make this kind of step in 2019, what else is he capable of?