Kolten Wong is figuring out left-handed pitchers

The peaks and valleys of Kolten Wong’s at times rollercoaster of a career have been well-documented at VEB. Through it all, however, a common denominator emerges: significant disparity in his performance at the plate against left-handed and right-handed pitchers. From 2015 to 2018, his wRC+ versus the latter stood at 106, or 6% above league average; when facing lefties, an abysmal 68. As for 2019, he has posted reverse splits: a 89 wRC+ against righties and 120 against lefties. Naturally, the question on my mind was “what changed?”

Let’s unpack everything in the above table. The two main takeaways are that:

1. Wong has cut his strikeout rate almost in half. Not only is Wong generating more hard contact per swing, but he’s putting bat to ball more often, period.
2. He has also displayed some sneaky “pop” in lefty-lefty matchups. Granted, isolated power (slugging percentage minus batting average) is up 21 points across MLB this year from the 2015-2018 timeframe, but the semi-subtle power surge is no minor factor in his overall wRC+ and OPS spikes.

I dug a little further to see if lefties were attacking Wong–or if he was responding–any differently in 2019 compared to seasons prior. Unsurprisingly, the most frequent pitch location was down-and-away. Of the 25 boxes in the images below, 34.9% of all lefty pitches in 2015-2018 and 37.4% this year were in the four in the bottom left. Note the changes in his swing rate, which dipped from 37.7% to 32.7%.

Courtesy of Brooks Baseball

Courtesy of Brooks Baseball

Wong has been more selective in chasing down-and-away, which has shown in a decreased whiff-per-swing rate in that area of the plate from 39.2% to 32.4%. That likely has had some spillover effect in freeing him up to focus more on pitches squarely in the strike zone, in which his swing rate has risen from 64.4% to 68.5% per Brooks Baseball. This revamped plate discipline likely has at least partial correlation with the lowered strikeout rate in addition to the newfound power. Zeroing in on pitches in the strike zone and refraining from as many ill-advised chases has resulted in a slugging percentage on pitches in the zone soaring from .387 all the way up to .529.

Of course, the elephant in the room is that Wong’s overall wRC+ of 96 this year is a measly three points above his career average, as both his wOBA and expected wOBA based on batted ball data against righties have taken a nosedive in 2019. At a cursory glance, an overly-aggressive, swing-for-the-fences approach may be the culprit. From 2015 to 2018, he sported a 44.5% groundball rate and 34.0% flyball rate versus right-handed opponents. Thus far in 2019, those numbers have essentially flipped to 35.6% and 44.6%, respectively.

In many respects, this season has been more of the same for Kolten Wong. He has turned in one of the best defensive and baserunning campaigns by any member of this ballclub, although relatively tepid hitting prowess has limited his holistic level of production. Wong has established himself as an above-average starting second baseman, but we have yet to see him sustain equally solid batting statistics regardless of the pitcher’s handedness.