What has gotten into Willson Contreras?

Just like every other Cubs player not named Javier Baez or Anthony Rizzo, Willson Contreras’s offensive production plummeted after the all-star break. Prior to the Midsummer Classic, Contreras was slashing .279/.368/.449, worth a wRC+ of 123. After the break, Contreras would go on to post a .200/.291/.294 line over 180 at-bats, amounting to a paltry 62 wRC+.

Contreras’s batted ball statistics from each half of the 2018 season are below.

Fangraphs

Fangraphs

There are a couple discernible statistics that help paint the picture of Contreras’s second half struggle. The first, is his ground ball percentage. It increased by nearly 10% in the second half, which would help explain his decline in power after the break, as he posted an ISO of .170 in the first half of the season and a .094 ISO in the second half. Secondly, his Hard% dropped nearly eight percentage points. When you’re hitting a lot of weak ground balls to your pull side (his Pull% increased by five percent), that’s a recipe for disastrous production at the plate.

Contreras posted a wRC+ of 100 in 2018, perfectly league average. But after posting a 123 wRC+ in his first two seasons with the Cubs, 2018 was a let down.

Fast forward to present day, Contreras leads all Cubs hitters with a wRC+ of 168, and has matched his fWAR of 2018 in just 24 games. So what changed?

Fangraphs

The first thing that sticks out is Contreras’s sharp decline in ground balls. For the first time in his career, Contreras is hitting fewer than 52% of his batted balls on the ground. Not only is his GB% lower than his career average of 52.7%, it’s at 41.7%, more than a 20% decrease. So he’s hitting more balls in the air, and the discrepancy between seasons is substantial in the charts below.

Baseball Savant

Baseball Savant

Contreras is also hitting balls with authority too, and that translates to a lot of extra base hits. Contreras has a Hard% of 39.6% in the first month of the season, more than seven percentage points higher than his career Hard% of 32.3%. Contreras already has seven home runs in the month of April, just three less than his total for the 2018 season.

Now, the question is if this is sustainable throughout the season? Probably not. Contreras currently has a BABIP of .341, which isn’t abnormally higher than his career BABIP of .322. But his .342 ISO, the highest among any qualified catcher, would have led all of baseball last season, regardless of position. That obviously isn’t sustainable. However, the early returns are incredibly encouraging, and it’s obvious that a tweak in launch angle has had a palpable effect on his production at the plate.