Regression a Relative Term for Rays’ Kevin Kiermaier


When Kevin Kiermaier was unstoppable at the plate to begin his major league career, everyone who had followed his career as a professional knew that he would not be that good in the long-term. We wanted to make excuses, and there were even a series of articles at various reputable outlets displaying belief in Kiermaier’s offensive ability, but the insidious feeling that he would cool off never dissipated. Indeed, it did eventually happen. On June 14th, Kiermaier had a 1.129 OPS, but he slipped to .971 by June 30th, and .858 entering today. In his first 26 major league starts, he batted in the ninth spot in the order just five times. With the Rays acknowledging that the league has begun to figure him out, he has batted ninth in 34 of his last 38 starts. We know how good Kiermaier’s defense is, but will he really be able to continue starting with his hitting only getting worse and worse?

It has to be acknowledged that Kiermaier is not nearly as good of a hitter as he was in his first few weeks in the big leagues. At the same time, however, this so-called “regression” has not been that bad. From his first major start until June 30th, Kiermaier hit to a .319/.361/.611 line in 123 plate appearances, but with a scary 25 strikeouts against just 7 walks. Since then, his line has slipped to .250/.317/.402 in 102 PA’s–still a respectable mark, especially at Tropicana Field–but his strikeout to walk ratio has actually improved to 18-8. Yes, the league has adjusted to Kevin Kiermaier, but Kiermaier is adapting in his own right, and doing quite a good job. You can try to shrug off Kiermaier’s increased patience and pitch recognition as a small sample size, but the difference is noticeable and reasonably significant. (To get the following data, I fiddled around with what’s available at Minor League Central).

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There are several other stats that I could have calculated, but the bottom line has been that Kiermaier is connecting more on his swings and doing a better job laying off of pitches outside the strike zone. If you want to say that the difference are so small, we can look at how the numbers fit into the context of other big league hitters. Kiermaier’s contact rate improvement takes him from the 204th-best hitter in the majors minimum 200 plate appearances up to 172nd, his whiff rate went from 212th up to 149th, and his outside-the-zone swing rate went from 187th to 97th. Kiermaier needs to continue those trends for the rest of the season, but the improvements that he has made and will continue to make should be enough for him to continue to hold his own at the plate at the major league level. It would have been nice if Kiermaier had kept up his outstanding start, but his struggles after that served as a wake-up call that he had to be more selective at the plate, and that shift will loom large for him moving forward.

It is becoming increasingly easier to see Kevin Kiermaier becoming the player we thought he could be entering 2014: an average or better major league centerfielder, a solid bottom-of-the-order hitter that provides incredible value with his defense. There is one disclaimer to that–Kiermaier still has to find a way to start hit left-handed pitching–but considering that he hit them well historically in the minor leagues, that is within the realm of possibility as well. Kevin Kiermaier was never going to sustain his unbelievable beginning to his big league career, but what he can sustain are the abilities that took from a 31st round pick into a big league option for the Rays. His plate approach has continued to improve even as his hot streak has faded away, and the Rays have reason to be excited about what he will give their team for years to come.