Craig Kimbrel’s High Second-Half Walk Rate in 2018 Coincided with Shifting Release Point

Craig Kimbrel finished 2018 with a stellar 2.74 ERA and 3.13 FIP in 62 innings, but his second-half walk rate was a high 6.23 BB/9. For a Cubs team searching for more strikes out of their bullpen, should they be concerned about Kimbrel’s excessive walks?

The Cubs undoubtedly pondered that aspect of his performance but perhaps they believe it to be an anomaly that can be addressed. From what I can tell, Kimbrel’s release point deviated around the same time that his command worsened. Specifically, the new Cubs closer’s horizontal release power flew away from his shoulder starting around July.

Around the same time Kimbrel’s horizontal release point deviated, his fastball velocity increased markedly.

Whether Kimbrel intentionally altered his release point to throw harder is unclear. Maybe he was trying to throw harder and, as a consequence, his release point shifted. Either way, Kimbrel’s added velocity wasn’t solely explained by a different release point since the correlation between velocity and release point appears mild (R= -0.3). Still real, just not not huge.

The walk rate is certainly a concern, one that isn’t alleviated by Kimbrel’s long layoff. But a three-year, $43 million contract is pretty solid evidence that the Cubs think the control issues are more anomaly than long-term reality.