The Regression Monster Has Come For Carson Kelly

[RandallPnkFloyd]

Image courtesy of Kiyoshi Mio-Imagn Images

On the last day of April, there was one hitter in Major League Baseball that featured a better wRC+ than Chicago Cubs catcher Carson Kelly. That hitter was Aaron Judge. Yes, as the calendar prepared to flip over to May, the only hitter demonstrating a more impressive offensive performance is the guy known for being perhaps the best pure hitter on the entire planet. 

We had no reason to think what was happening was sustainable. Nonetheless, Kelly maintained a 257 wRC+ through nearly 70 plate appearances. His 22.4 percent walk rate led the league. Each of his average (.360), on-base percentage (.507), and isolated slugging (.480) fell somewhere in the top five among hitters with at least 50 PA. His Hard-Hit% sat sixth, at 60.6. 

There were plenty of encouraging things happening underneath the surface, too. Kelly's chase rate over that stretch was just 12.8 percent. Even Kyle Tucker, who was as choose-y as anyone in the Cubs lineup, was expanding the zone at a 22.8 percent clip. Kelly's whiff rate was just 7.0 percent, while his contact rate sat at nearly 84 percent. 

It all had Kelly looking like not only the ideal signing for a Cubs team looking for a bit of an offensive bump from behind the plate, but one of the best signings in recent Major League history. Of course, the regression monster comes for everyone eventually, especially when you're talking about a veteran catcher with only a modest history of offensive success. Now halfway through May, the monster has consumed him almost entirely. 

While we're obviously looking at a smaller sample only halfway through the month, Kelly's output nevertheless has dwindled quite gravely. Going into Friday's game against the White Sox, he's hitting only .182 this month; his OBP has plummeted to .289. Part of that is due to the reversal of his strikeout & walk rates. The former has doubled to 18.4 percent while the latter checks in nine points below his mark through April 30th (13.2 percent). The power has been nonexistent compared to what he turned in last month, with just a .121 ISO through two weeks of May. His wRC+ this month is at just 74. So not only has he not been the second-best hitter in baseball, he's now 26-percent worse than league average.

[Editor's Note: Kelly did record two hits, including a double, and a walk in five plate appearances in the series-opener on Friday. Nevertheless, his stats remain in precipitous decline from his otherworldly start.]

Worse yet is that at least some of these struggles are due to Kelly's own lapse in the approach. His chase rate has more than doubled (26.1 percent) despite almost no movement in his overall Swing%, which means that he's exchanged a disciplined, in-zone approach for a useless expansion of the zone. He's making contact at a rate six percent lower than he did last month, and even that's with only a two percent dip in the rate at which opposing pitchers come into the strike zone. 

Without the level of discipline that Kelly was able to showcase in April, the most telling trend in all of this emerges: 

As it would turn out, it's harder to generate quality contact when you're not concentrating your swings within the strike zone. Or at least it is when you're a hitter without elite upside that has a delicate balance to maintain in order to find offensive success. Instead, you make softer contact. Softer contact means less batted ball luck and less elevation. Not that his April BABIP was tremendously high (.289), but it's at .200 in May. His GB%, on the other hand, has spiked from 40.0 percent in April to over 60 percent halfway through May. It's not a difficult mystery to solve. Kelly's inability to drive the ball is derived largely from a ballooning of the zone in which he's willing to swing. 

It's unfortunate reality for Carson Kelly that his (expected) regression has been wrought almost entirely by his own hand. Pitchers haven't altered their approach much, either in terms of usage or zone. But Kelly's loss of discipline in the approach bears the weight of such regression.

What's even worse is the timing of the offensive step back. Without Ian Happ in the lineup, Craig Counsell had shifted to a willingness to deploy both Kelly & Miguel Amaya in the lineup, with Kelly getting two of his last three starts as the team's designated hitter. Given the struggles, though, it doesn't appear to be a role he's long for, ynless the approach finds some refinement and a return to form in a most expedient fashion.

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