Kevin Long: Miracle Worker?

Understandably new manager Davey Martinez has been grabbing all of the headlines this spring. Bringing camels to camp all in service of a hump day joke will do that. However, the new coach I’m most interested in is Kevin Long, the hitting coach.

Many diehard baseball fans will know Long’s name from the launch angle revolution of 2016, where seemingly every baseball writer in America wrote about players trying to hit more fly balls. Nats fans in particular will likely know him in association with Daniel Murphy going from everyday above average hitter to hitting god. You also likely know the oft cited stat that Curtis Granderson had seven career home runs against left-handed pitchers until his first season with Long and the Yankees, when he hit 16.

However, entering the research phase for this post I would have been considered skeptical of his miracle-worker status. For years I’ve said hitting and pitching coaches don’t have much of an impact. The guys they’re working with are at such an elite level and have been working on their games for over 25 years; there’s not much someone can teach an MLB player. But I’m a convert now and I bet you will be too at the end of this.

To try to get a better idea of Long’s impact as a coach I wanted to compare hitting stats for the players he has coached before and after he became their coach. Long’s coaching history is seven years (2007-14) with the Yankees and three (2015-17) with the Mets. That’s a healthy number of hitters to pull from.

But first we want to make sure we cut as much of the noise out of this data as possible. A hitter could happen to have a career year his first year with Long, then drop off the face of the earth after. We don’t want to credit Long unless we can see evidence of a long-term difference. So I cut down the hitters selected to those with at least 750 plate appearances across a three year period, both pre and post-Long. That should give us sufficient bodies of work to compare.

That leaves us with 19 hitters from the Mets and Yankees. The last step was to answer what to do with Curtis Granderson, who fit the criteria above both with the Yankees and later with the Mets. I ultimately decided that only Granderson’s Yankees tenure should be included, since it’s difficult to argue that he benefited from being re-introduced on the Mets after only a year apart.

The table below shows the 19 hitters and their change in walk and strikeout rate, isolated slugging, batting average, on-base percentage, slugging percentage, wOBA and wRC+. A positive number means they improved in that stat with Long as their hitting coach. The most important stat here is wRC+, which takes a holistic view of offense and adjusts for league stats and park, which improves the across decade comparisons.


Three things stand out to me looking at the overall numbers.

First, that hitters under Long improved by two percentage points in wRC+; which seems pretty modest. However, for context, I pulled every hitter in baseball that fit the criteria used above for 2015-17 and 2007-09 and were 25 and older like all of the Mets and Yankees hitters were. The all MLB hitters actually saw their wRC+ decrease by 5.8 percentage points. Suddenly that 2 percentage point improvement is now 7.8, which isn’t so modest.

Second, the improvement is fueled by changes in power; 14 of the 19 hitters saw an improvement in their ISO when working with Long. The average improvement of .021 is similar to the power difference between Michael A. Taylor and Anthony Rendon.

Third, six players saw their wRC+ increase by 10 or more percentage points, while three saw their wRC+ decrease by 10 or more. Unsurprisingly, all three were 33 or older when they started working with Long. So far, I haven’t tried to account for age, which can make a big difference. You probably wouldn’t be surprised that players in the prime ages of 25-32 would improve while those 33 and older would get worse.

To get a better control of that, I’ve binned the Long and all MLB players by their age group 25-32 (12 Long hitters) or 33+ (seven Long hitters). The Long hitters who were between 25-32 raised their wRC+ by six percentage points, while all MLB players between 25-32 saw their wRC+ decrease by about three percentage points. Yes, the younger hitters weren’t automatically improving like one would assume. Meanwhile, the Long hitters above 33 saw their wRC+ decrease by an average of five percentage points, but that was still much better than their peers who had a 12 percentage points decrease. Mitigating poor results is also a handy tool for a coach to have.

The last grouping I looked at was handedness, since I’d seen some writers say Long is particularly good working with left-handed hitters. I actually found the opposite to be true; the six switch hitters saw their wRC+ rise by six percentage points and the five righties were right behind them at an improvement of 3.6. The eight left-handed hitters performed the worst, with their wRC+ decreasing by two. If Long really does work better with switch hitters that could be great news for the Nats considering their offensive black hole, Matt Weiters, is a switch hitter.

Yes, 19 hitters is a small sample size to judge from and because of that I’m still skeptical of Long the miracle worker, but he’s clearly a very good hitting coach. Overall, it’s still difficult to say exactly what Long does to fuel these changes. I looked into each player’s batted ball statistics and only Daniel Murphy had a substantial difference in his groundball to fly ball ratio.

I think my original hypothesis still stands, a hitting coach isn’t making huge changes to a MLB player’s approach or swing. If I were to guess at what the difference is, I think I overlooked the mental aspect of the job. Hitters have about 125 milliseconds to decide whether to swing or not, that doesn’t leave much room for doubts. If a coach is particularly adept at getting his hitters in the right frame of mind, they’ll likely be more successful. And if you believe the rave reviews, which you should, Long is that kind of coach.

This post was updated to reflect an accurate comparison for Jose Reyes and Neil Walker, who joined the Mets in 2016. They are now compared as 2013-15 vs. 2016-17 when on the Mets. The table and text have been changed to reflect that.

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