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Paul DeJong’s 2018: At the plate

DeJong’s decreased production wasn’t underperformance, it was regression—but it was still solid.

MLB: St. Louis Cardinals at Detroit Tigers Rick Osentoski-USA TODAY Sports

Shortstop has been a bit of a revolving door for the Cardinals since Ozzie Smith’s retirement.

Over 20 years, from 1997 through 2016, the redbirds had 22 different players log innings at short. Two others have been added to that list since then, but one of them has already made quite the mark.

After just two shortened seasons, Paul DeJong now sits second in total fWAR for Cardinal shortstops since 1997.

His single season performances rank as the fourth- and fifth-best by fWAR in that time frame, behind two years of prime Edgar Renteria and Jhonny Peralta’s excellent Cardinal debut.

DeJong didn’t seem to be discussed much this year, beyond the news of his six-year extension before the season and the hand injury that kept him out during the middle of the year.

It was a quiet year, really. His bat fell off in terms of actual performance. His glove was exceptional. He built on his 3.0 fWAR in 2017, raising that number to 3.3 last season.

As someone who didn’t really get to see Ozzie play every day and remember it, I always wanted to see the Cardinals lock up a steady shortstop and stop the parade. It was fun to watch Renteria, David Eckstein and Rafael Furcal, but I’ve always wanted a longterm solution.

DeJong has quietly become just that, though maybe not in the way we expected when he was a rising prospect and budding rookie.

I think it’s worth acknowledging how he not only maintained his rookie value, but built upon it in 2018. I want to spend some time looking at his season. His glove was the real story, but we’ll look at defense next week. This week, I want to take a look at his bat, and why his performance didn’t fall off as much as one might expect.

The luck of 2017

One can’t deny that DeJong’s 2017 was a much better year at the plate when looking at actual production. He posted 122 wRC+ and reached the 25-homer plateau in just 443 PA. His .857 OPS had him in Rookie of the Year discussions.

A lot of that success was built on some serious batted ball luck. You see it immediately when noting his .349 BABIP. Unless DeJong was about to become one of the greatest hitters in the game, that was bound to drop.

The benefit of that luck really manifested in his power. DeJong’s .532 slugging percentage was impressive to see, but Baseball Savant’s data shows that he greatly outperformed expectations on barreled balls and solid contact. His wOBA (1.330) was a whopping .220 points higher than his xwOBA (1.110) on those contact types in 2017.

Don’t get me wrong, having that high of an expected performance level on those contact types is still impressive. For reference, Matt Carpenter’s xwOBA on barreled balls and solid contact in 2018 was 1.006. The point is that outperforming your expectations by that much is bound to send you soaring back down to earth eventually.

Looking at all plate appearances and contact types, DeJong’s 2017 xSLG was .479, which was .053 lower than his actual performance.

What that means in evaluating 2018

DeJong’s 2018 was undeniably weaker, to get that out of the way now. His wRC+ fell 20 points, from 122 to 102. His xwOBA, however, only dropped .010, from .334 to .324.

That really isn’t that big of a difference—especially when compared to the 20-point drop in wRC+.

The 2018 season actually points to a lot of improvements in DeJong’s approach. He might’ve actually overcorrected in a lot of areas. If he can come back and attack those parts of his game to find the middle ground in 2019, we may see a bit of a breakout. Either way, he’s still an above-average hitter. Let’s take a look at the improvements in his peripherals.

Plate Discipline

BIS’s plate discipline stats over the last two years look like this:

Paul DeJong, Plate Discipline, 2017-2018

Season O-Swing% Z-Swing% Swing% O-Contact% Z-Contact% Contact% Zone% F-Strike% SwStr%
Season O-Swing% Z-Swing% Swing% O-Contact% Z-Contact% Contact% Zone% F-Strike% SwStr%
2017 33.6% 72.3% 51.6% 59.2% 82.2% 74.2% 46.5% 61.4% 13.3%
2018 29.8% 66.6% 45.8% 55.3% 87.9% 75.9% 43.5% 58.4% 11.0%
DIFF -3.8% -5.7% -5.8% -3.9% 5.7% 1.7% -3.0% -3.0% -2.3%

He dropped his swing percentage by 5.8%. That’s a pretty big decrease. Looking at the 1.1% increase in his contact rate, it’s easy to be disappointed that it wasn’t a larger jump. But it seems clear that DeJong was prioritizing zone contact over anything outside—his Z-Contact went up nearly 6% while his O-Contact fell by almost 4%.

The positive is a decrease in swinging strikes, which fell by 2.3% last season. Still, his swing rate inside the zone fell even more than his swing rate outside it. One has to wonder if that more cautious approach has limited someone like DeJong, who seemed in 2017 to be the model of the new-wave, all or nothing batters.

It did, however, result in a better on-base ability outside of putting the ball in play. DeJong’s walk rate rose 2.6% in 2018. His strikeout rate fell 2.9%.


The result is some interesting changes in contact. Ultimately, DeJong lowered his soft contact and increased his hard contact. On the surface, sounds good, right? His Soft/Med/Hard splits went from 21.4%/42.2%/36.4% in 2017 to 18.6%/42.8%/38.7% in 2018.

His barrels and solid contact did go up in 2018, even if it was less than a percentage increase. The problem came with the balls he just missed. Here are his radial charts from the past two seasons showing number of balls in play grouped by contact quality, courtesy of Baseball Savant:

He was topping or just under a considerably larger number of balls in 2018 than the previous season. Both of those contact types have xwOBAs under .100.

DeJong made great strides in improving his eye in 2018, which resulted in a pretty solid change in walks and strikeouts. The problem in 2019 will be squaring up the balls he does swing at, turning them into quality contact, and making sure he isn’t overcorrecting in taking pitches inside the zone that could be worth the swing.