Should Teams be Worried About Craig Kimbrel?

by: Jeff Adams – February 6th, 2019

Entering his age 31 season, Craig Kimbrel has been asking teams for a deal somewhere in the neighborhood of six years. That might have been a reasonable ask at the beginning of the off-season, but it’s obvious something is changing as we sit here a few days until Spring Training with most of the major free agents without a home. These days, teams are becoming more and more unwilling to contribute resources to free agents, especially pitchers. Age, which used to mean value and reliability, is now seen as a liability.

As a closer, Kimbrel has thrown fewer innings than a similar aged starting pitcher, but relievers seem to have a harder time getting an extended contract at his age. Due to his heavy reliance on his big fastball, teams expect that he may lose a tick or so over the next couple years, let alone the six he’s asking for. In short, teams are skeptical of his value in the coming years and wonder whether a flame throwing closer like Kimbrel could maintain his production for another 6 years.

In a case like this, a team might compare him to similar pitchers over their age 31 to age 36 seasons to see how he could perform over his next contract. However, since making his debut at 22, Kimbrel has put together a career that very few pitchers have ever come close to imitating. By similarity score, Kimbrel has no close historical comparisons as his closest competitor, Kenley Jansen, is only several months older than he is. As a 7-time All-Star closer who converts saves at a 90.7% clip (a full point and a half better than Mariano Rivera), you might think that teams would be clamoring to sign him. Instead, teams appear worried that he will remain effective in the coming years as he gets on the back side of his age curve. Aging pitchers tend to start shying away from the fastball as it loses velocity in favor of off-speed. For pitchers with more than two pitches, this might be sustainable as they will be able to vary their offerings enough to fool batters. Kimbrel is not one of those pitchers. Without an applicable comparison and not enough pitches to fall back on if his fastball falters, evaluating Kimbrel won’t be easy. In an effort to do so, I am going to attempt to use trends in his fastball usage to determine whether Kimbrel is signaling a decline or continued dominance.

Over the course of his nine-year career, he has only thrown two pitches: a four-seamer and a knuckle-curve. He throws his fastball a little over twice as often as the breaking ball. If Kimbrel starts to lose effectiveness on his fastball, the curve, which he only threw for a strike 33% of the time in 2018, is his only backup. Due to that, any drop-off in fastball velocity would be quite concerning.

As we see from this graph, the 2018 season was the first time he has seen a noticeable velocity drop as his average release speed fell by nearly 1.2 mph. This alone is probably what has scared off a lot of teams. Looking at overall pitch usage, it appears that Kimbrel is taking the normal route of an ageing pitcher by relying less and less on velocity. The 4.3% drop in overall fastball usage is the largest season-to-season change of his career and is directly correlated with a decrease in fastball velocity. However, I’m not sure if looking at overall usage stats tells the whole story of what’s going on here.

Compared to the rest of his career, the last two years have seen his heaviest reliance on the fastball to get the strikeout with 73% and 65% of K’s coming on the pitch in 2017 and 2018, respectively. A 12-20% increase over his 7-year average of 53% is definitely something interesting. This uptick in the fastball being the strikeout pitch made me wonder if his four-seam usage has become more strategic in the last two years, so I looked at his four-seam usage across the various counts.

The last two years are again the most interesting data points here as it’s obvious that Kimbrel has made two primary adjustments. In 0-0 counts, he has dropped his fastball usage by nearly 15%. This appears to be a conscious change since both 2017 and 2018 are within a percentage point of each other. There’s no telling whether this is a Kimbrel driven change or a Red Sox directive (at least without analyzing every Sox pitcher). Considering that he faces an 0-0 count on every batter, this change might account for a lot of the overall decrease in fastball usage. Instead of the decrease coming from a lack confidence in the velocity, it might be coming from a change in how he is using the fastball.

In two strike counts, there has been a noticeable increase in his fastball use. He threw the fastball 84% of the time in a 1-2 count in 2017 but has dropped that back down to 68% in 2018. Overall, he has dropped his early count fastball usage while ramping it up in 1-2 & 2-2 counts. To me, this signals a changing strategy for Kimbrel where he varies his look early on and relies more on the fastball in higher leverage counts. On the surface, it appears that he is falling into the mode of the faltering power pitcher by going to the off speed more often. However upon a deeper look at his situational pitch calling, the more likely story is that Kimbrel has simply shifted his strategy in recent years.

While the velocity dip in 2019 is a little concerning, he’s still throwing 97 mph which is still in the 96th percentile among all MLB pitchers. I believe we’re seeing one of the most dominant pitchers of our time evolve, rather than decline. A six-year contract may be too much to ask for as a 31 year-old reliever, but I’d put money on Kimbrel adding to his Hall of Fame plaque in 2019 and someone should have signed him by now.

Cover Photo courtesy of Boston Common-Magazine

Data courtesy of Fangraphs and Baseball Savant

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