Will Jacoby Ellsbury’s power ever come back?

Red_Sox_094_Jacoby_Ellsbury (2)
Will Jacoby Ellsbury ever sniff 30 homers again?

Jacoby Ellsbury can do a lot of things to help his team win a baseball game. He hits for a high average, plays top-notch defense at a premium position, and last year he was the best baserunner in all of baseball. Yet, save for one season, hitting for power is one skill that hasn’t really been a part of Ellsbury’s game. The exception, of course, was Ellsbury’s 2011 season. The one where he erupted for 32 homeruns, turning him from a good player to an elite player. But after that magical season, he reverted back to his old self — a solid contact hitter who provides value with his legs more so than his bat.

So, what the heck happened in 2011? And why did it stop happening?

The answer lies in Ellsbury’s homerun to fly ball rate, or HR/FB. Ellsbury wasn’t really hitting any more fly balls in 2011, but a good portion of them were clearing the fence. Both before and after 2011, less than 6% of Ellsbury’s fly balls left the ballpark. Yet in 2011, that ratio nearly tripled to 16.7%. While a hitter’s HR/FB can be fluky, it’s almost never that fluey, especially when you consider Ellsbury’s 2011 wasn’t even that small of a sample size. When it comes to HR/FB, we can generally get a reasonable understanding of a hitter’s true talent level after just 50 fly balls. As the Red Sox lead-off hitter in 158 games in 2011, Ellsbury came to the plate 732 times and hit 192 fly balls. This seems to imply that Ellsbury was doing something differently in 2011.

Taking a closer look at how those fly balls were distributed would give us some insight into what may have changed. Unfortunately, one would need HITF/X data, which is not publicly available, to adequately analyze Ellsbury’s batted ball trajectories. What is available, is data from MLB Gameday on  how far batted balls traveled. For non-home runs, a ball’s distance is recorded by where the ball is fielded, weather in the air or off the ground; while, a home run’s recorded distance is up to the point where the ball is obstructed, and does nothing to predict the ball’s landing point.

This data is obviously flawed. The distance traveled by a ball is not necessarily representative of how hard (or even far) it’s hit. And I would guess that home runs are probably short-changed more than other flyballs since they are more likely to be obstructed by things like outfield scoreboards and bleachers.

But really the only alternative is to look at his 2011 outlier hr/fb rate and throw our hands in the air. This method should shine at least some light onto whether or not Ellsbury’s 2011 fly balls were at all special.

Jacoby  Ellsbury's fly balls
Note: This data measures total distance actually traveled, not the ball’s predicted landing spot.

Clearly, a much greater share of Ellsbury’s fly balls traveled over 350 feet in 2011, which is usually far enough to leave the ballpark. What really stands out is that the two sets of data have very different distributions. His 2012-2013 looks a lot like a normally distributed bell curve, while in 2011, his fly balls were more concentrated between 320 and 400 feet. This makes sense: a pretty good portion of Ellsbury’s 2011 fly balls went for home runs, which means they were probably obstructed shortly thereafter. If they were allowed to keep going (or if their landing spot were estimated), they surely would have traveled much further.

The average distance of a 2011 fly ball was only eight feet further in 2011, but most of his home runs were stopped abruptly between 350 and 400 feet, which greatly skews the numbers. The disparity between the distances would have been much higher if the distances of his 32 home runs were more accurately recorded.

Although the data are a little sketchy, they seem to imply that Ellsbury was in fact hitting the balls with more authority in 2011, but it’s hard to say why. It could be that he was stronger in 2011 or that his swing was slightly different, or it could just be random noise stemming from imprecise data. There’s really no way to know.

It’s worth mentioning that Ellsbury missed three months due to a shoulder subluxation in early 2012, which may have stunted his power. That injury’s pretty far behind him now, but it’s possible that his swing hasn’t been quite the same since If that is the case, though, it’s probably not going to fix itself now, two years after the injury.

Most likely, 2011 was nothing more than a blip on the radar and the real Jacoby looks more like the 2012-2013 iteration. The past two seasons have provided us with plenty of more recent data that also happens to jive with Ellsbury’s career numbers. That being said, his 2011 did happen and probably has some value in predicting the likelihood of an Ellsbury fly ball turning into a homer going forward. All told, Ellsbury’s 2014 HR/FB will almost certainly be well below the 17% we saw in 2011, but still a bit higher than the 6% we’ve seen since. His career rate of 8.4% is probably a reasonable expectation going forward, which over  700 plate appearances, would give him about 12 or 13 dingers — not completely punchless, but still just a shell of his 2011 self.

Photo from Parkerjh at the English language Wikipedia [CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

About Chris

Chris works in economic development by day, but spends most of his nights thinking about baseball. He writes for Pinstripe Pundits, and is an occasional user of the twitter machine: @_chris_mitchell
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