Kolten Wong, Unheralded Master of Plate Discipline

If you know one thing about Kolten Wong, you probably know that he’s a great defender. Honestly, great defender might be underselling it. Since 2014, his first full year in the bigs, he’s third in Defensive Runs Saved at second base. Maybe UZR is more your speed? Wong is third there, too. This isn’t some trick of innings played, either — he’s fourth in UZR/150 among qualifiers. He hasn’t won a Gold Glove yet, but it’s not because he doesn’t deserve it.

If you know Kolten Wong for a second thing, you probably know him for the endless flashes of potential, the bumpy road he’s followed throughout his major league career. In 2013, when he’d barely had a cup of coffee in the regular season, he got picked off of first base to end a World Series game. After two average-ish seasons in the majors, he found himself playing the outfield (?!) so that the team could squeeze more at-bats out of… um… Matt Adams? Brandon Moss? Greg Garcia? Mike Matheny-run teams had some interesting substitution patterns, let me tell you.

In any case, whatever you know about Kolten Wong, elite plate discipline probably isn’t on your list. After all, Wong is on the field for defense. Take a look at his yearly wRC+ numbers, starting with his first full year: 90, 96, 85, 107, 98. Those numbers are totally acceptable for a premium defender (Wong’s career wRC+ bests Andrelton Simmons’), but they also lead to batting at the bottom of the lineup more often than not.

Here’s the thing, though: Wong is certifiably great at controlling walks and strikeouts. It’s not just a 2019 thing, though it’s certainly been the case so far in 2019. Take a look at the list of qualified batters with more walks than strikeouts this year:

Next, let’s make this a little more representative of player skill. Here’s the same list, except subtracting intentional walks and adding in HBP (the strikeout rates will look different because I’ve subtracted out IBB’s from plate appearance totals):

Now, obviously this is only one year’s data, so it’s time to talk about statistical stability. At around 100 plate appearances, you often hear that strikeout rate “stabilizes.” FanGraphs has published many studies of reliability and stability, and that’s near the threshold most of those studies agree on. On the other hand — take a look at a 25-game rolling sample of Wong’s strikeout and walk rates:

Not completely stable, is it? That’s because while you can say the metric reflects skill level reasonably quickly, players’ skill level isn’t constant. It’s a tricky road to walk, because 100 PA samples really are enough to tell us something about a player’s current true talent level. The only problem is, that true talent is changing all the time.

Still, though, I’m willing to give Wong the benefit of the doubt. You might not notice it, because HBP numbers don’t show up in walk rate, but Wong has always excelled at getting on base without putting the ball in play. Let’s look at the same metric we did before, unintentional walks plus HBP’s, for every year of Wong’s career:

Parse the data this way, and you can see that this isn’t something new. 2019 represents a new peak, but he’s been building towards it for years.

Let’s hone in on that 2019 data, though. If this newfound plate discipline is for real, Wong’s floor is tremendously high. If that’s the case, however, then theoretically Wong should have made some changes between 2018 and 2019 that unlocked this new level of performance. Take a look at some relevant stats for the last two years, and it mostly looks like that isn’t the case:

Wong is swinging at more pitches out of the zone and making contact less often. He’s swinging at more strikes, which should help keep his strikeouts down, but it’s still not what you’d expect to see from someone who started taking more walks.

Buried in these mostly uninteresting data points, though, is something fascinating. Wong’s first-pitch strike rate has gone way down. This year, Kolten Wong gets a first-pitch strike against him less often than all but six qualified batters. No batter in baseball swings more than Wong and gets fewer first strikes for his trouble. As Dan Szymborski noted in his look into Aaron Nola’s struggles, first-pitch strike rate seems to matter for walk rates. Let’s dive right into Wong’s 2019 first pitches to see what the heck is going on.

First of all, it’s hard to avoid 0-1 counts if pitchers don’t help out a little bit, and that’s certainly the case here. Wong has seen pitches in the strike zone in only 45% of plate appearances, against a league-wide average of 51.4%. That seems… suboptimal on the pitchers’ part. Kolten Wong has a career .129 ISO, but pitchers are nibbling out there. To some extent, that seems justified — if you’re too cavalier with Wong, you might get Chacin’ed:

On the other hand, “don’t throw center-cut 89 mph fastballs” isn’t just advice for facing Kolten Wong; it’s advice for life. Overall, Wong has been aggressive enough to keep pitchers afraid of him. He’s swung more often than league average at first pitches that are in the strike zone, and he’s doing damage when he swings. He’s put 13 of the 19 strikes he’s swung at into play, and with a .460 xwOBA (league average on first pitches in play this year is a .392 wOBA), he’s getting serious production on those swings.

Okay, so maybe some of pitchers’ reluctance to groove Wong a first-pitch strike is justified. It’s a small sample size, but a small sample size of a good result beats no evidence of that result any day. When pitchers don’t find the zone on the first pitch, Wong has also improved. Take a look at some first-pitch plate discipline numbers, for Wong as well as for the league as a whole:

Well, that’s a neat trick. Wong has barely swung at first-pitch balls this year, but he’s maintained his aggression on pitches in the zone. Even if the overall decline in first-pitch strikes is unsustainable, his underlying behavior points the correct direction.

Want another reason Wong is seeing more first-pitch balls? I mentioned up above that he has a .129 ISO for his career. That’s true, but he also has a .224 ISO in 2019. Now, to a large extent, this power is a mirage. Wong’s slugging percentage is more than 100 points higher than his xSLG, per Baseball Savant. Wong has the potential to hit for a little power, but probably not like his current clip. Still, though, Wong has given pitchers something to worry about, and that might depress the number of first-pitch strikes he sees for quite a while.

Up above, I said that Wong’s newfound plate discipline gives him a high floor. Let’s delve into that a little more, while still recognizing that, yeah fiiiiiiine, he probably won’t run strikeout and walk numbers quite this good all year long.

Let’s say that our goal is to make Kolten Wong a league average hitter using his current walk, strikeout, and HBP rates. This is a pretty straightforward exercise. League average wOBA so far this year is .318. I’m using wOBA over wRC+ for ease of calculation. Given that I’m not using any actual values for production on contact, I think it tracks well enough. Since we know the wOBA factors for walks, strikeouts, and HBP’s (.691, 0, and .720 respectively) and the frequency with which he gets each of those outcomes, we can solve for the wOBA he needs to achieve on contact to get to .318 overall:

There’s our hypothetical, league-average Wong. Without some context, though, it might be hard to appreciate what an easy bar this is to clear. After all, .293 is just a number. Well, think of it this way. Across all of baseball this year, wOBA on contact has been .381. This year is the year of the home run, but wOBA on contact has always been higher than overall league average. Last year, league-wide wOBA was .315 and wOBA on contact was .368. The year before, those numbers were .321 and .373, respectively. wOBA is tied to on-base percentage, but wOBA on contact has stayed in a tight (and high) range for the last five years.

Let’s take this a little further and provide some examples. Wong could get results that were 77% as good as league average (.293/.381) and still be an average hitter overall. Last year, exactly six hitters put 200 balls into play and did worse than that. That list is a real who’s who of rough 2018s — Jonathan Lucroy, Delino DeShields, Alcides Escobar, Joe Panik, Dexter Fowler, and Christian Vazquez. They combined for negative WAR, even with two of them playing catcher. The highest wRC+ in the group was Panik’s 75.

Wong has never produced that poorly when he makes contact. The closest he came was in his disastrous outfield-adventure in 2016, when his contact quality was 80% of league average. Last year he came in at a solid 88% of average. And again, even if Wong ends the season with a wOBA on contact this low, that would make him a league average hitter overall.

Getting on base via walks and HBP’s and limiting strikeouts does more than just raise Wong’s floor. It raises the chances that he could put up a star-level season. If he replicates last year’s relative contact quality on the year as a whole, that gets him roughly to a 110 wRC+. If he replicates last year’s contact quality the rest of the way (banking his above-average contact so far), that’s a 113 wRC+. If he goes really nuts and ends the year with league-average contact quality, we’re looking at a 120 wRC+.

Kolten Wong has been a 2.9 WAR/600 PA player for his career with a 95 wRC+. His defense and baserunning are tremendously valuable. If he starts putting up 120 wRC+’s, that looks more like a 5 WAR/600 season (numbers extremely rounded, because we’re talking in theoreticals here). Is this wish-casting? Sure. It’s not completely out of the realm of possibility, though. We’re not turning Kolten Wong into Mike Trout; we’re making him average when he puts the ball in play.

That, in a 1700 word nutshell, is what’s so amazing about Wong. Watch a Cardinals broadcast, home or away, and you’ll probably hear the announcers comment on his defense. If he has an extra-base hit, they might mention that he sometimes shows surprising pop. It’s almost a guarantee, though, that they won’t mention his strikeouts and walks. It’s not sexy. It’s not a talking point. It’s just an incredibly valuable, near-invisible skill that turbo-charges Wong’s value, whether he’s hitting well or not.