Batted Ball Data
Let’s begin with the batted ball data. Kershaw is well known for allowing little hard contact and for generating plenty of strikeouts, at least in his prime. The current version of Kershaw is not much like the prime version though, so let’s compare the old with the new, ala any good infomercial.
DISCLAIMER: What may alter some of the contextual data so drastically despite similar raw numbers, meaning his rank on leaderboards for these various statistics, is the fact that fewer pitchers qualify as “qualified starters” during the 2017-2019 stretch since fewer starters throw enough innings to qualify in comparison to the other sections of Kershaw’s career.
Additionally, the pitching landscape has gone apparently from aiming for groundballs to aiming for flyballs, as pitchers have shown they are willing to play into the hitters’ newfound desire to elevate the baseball.
In comparing groundball, flyball, and line drive rates, the old and new versions look a lot alike. In his first three seasons with a major workload, and solid results (2009-2011) Kershaw’s groundball rate settled in at 41.1% (good for 88th overall amongst qualifiers), sandwiching him between Homer Bailey (yikes) and Kyle Davies (remember him?), both of whom had ERAs well over 4.00 over this three-season span.
From 2012 to 2016, Kershaw’s groundball rate spiked to 48.6% over four of his best seasons, placing him 50th amongst qualified starters over that time span. His 48.5% mark from 2017 to 2019, nearly identical to his mid-career mark, places him 17th in all of baseball, indicating a relative decrease in groundball rate, which makes sense contextually, as league-wide flyballs have gone up since the advent of the so-called “launch angle revolution” that began a few seasons ago with Justin Turner, “Dodger Killer” Daniel Murphy and J.D. Martinez among others.
While the difference in groundball rate between his early career and mid-to-late career is marked at around 7%, what may be more notable is his consistency in creating ground balls even as they have decreased across the MLB. This demonstrates that the lefty hurler is having no trouble getting hitters to do what he wants them to do for the most part, which is to beat the ball into the ground for an out.
Less importantly to Kershaw’s groundball heavy game in recent years, but just as telling, are the changes and continuities in his flyball and line drive rates over the same stretches. While early on his career his flyball rate was 40.6% (32nd in baseball), from 2012-2016 his flyball rate was 30.7% (122nd in baseball) and from 2017-2019 his flyball rate has been 31.0% (63rd amongst qualified starters). This is a major decrease of nearly 10% from his early career to later career.
And yet, there seems to be little change between prime Kershaw and post-prime Kershaw in terms of groundball rate or flyball rate. Both seem to have stabilized in the 2012-2013 point in his career development and have remained mostly stagnant up until this point, despite noted decreases in velocity and despite changes in hitting as philosophy over this stretch.
What has this manifested itself as though in terms of results, mainly concerning differentiating prime from post-prime Kershaw? Put another way, if groundball rate and flyball rate have not changed over this stretch, why the disparity in ERA or FIP, or more simply in overall dominance?