The Curious Case of Jason Heyward

Jason Heyward’s first year with the Cubs was certainly a year to forget. So should we expect more of the same in 2017? Let’s take a look at Heyward’s career and comparable players in an attempt to find out.

The night was October 26, 2016.   Game 2 of the World Series,  and the Chicago Cubs were down 0-1 to the Indians in their chase for the city’s first title in over 100 years.  And where was the Cubs’ highest paid hitter, Jason Heyward?  Riding the pine for the second straight game, benched because of an inability to produce at the plate.  To a large extent, Heyward must have been thinking: how the hell did I get here?  Meanwhile, the Cubs front office was concurrently wondering whether they fantastically overvalued their prized off-season acquisition.

To answer these questions, let’s examine Heyward’s superstar pedigree, his spectacularly bad 2016 offensive performance, and his prospects for next season.  (Spoiler alert for 2017: he’s going to bounce back.)

A Cant-Miss Prospect

A first-round pick by the Atlanta Braves in 2007, Heyward tore up the minors for three seasons before forcing his way onto the Big League team to begin 2010.   Heyward was the consensus number one prospect in baseball at the time, generating sentiment like the following scouting report from

There’s little Heyward can’t do. He’s got great bat speed, with the ability to hit for average and power. He has an excellent knowledge of the strike zone. He’s got a plus arm from the outfield, runs well and is an excellent base-runner. His makeup is off the charts. Oh, and he’s only 20…

Heyward owns a slightly unorthodox swing: his hands start very low and close to his body, he has a bit of a hitch, and the swing has very little loft.  From where I sit, the swing seems to lack the fluidity exhibited by other superstar left-handed batters.


The lack of loft means that he likely will never tap into the massive home run power that normally comes with that type of bat speed, and the hitch means he may have trouble getting to inside pitches with authority.  Nevertheless, based on his superb minor league results and first-round pedigree, expectations across the industry were sky-high for the talented, young left-hander.

Major League Ready

Heyward announced his arrival on the world stage in 2010 by launching a home run to the right field seats in his first Major League at-bat for the Braves.  He would ultimately play five seasons for Atlanta, putting up solid — albeit at times not spectacular — offensive numbers to go along with excellent defense.  While his offensive prowess may not have quite lived up to immense expectation, his defense and base running made him one of the most valuable outfielders in baseball during the Atlanta seasons of 2010-2014.  Still just 25, Heyward was set to cash in as a free agent after the 2015 campaign.

Fully aware of how expensive Heyward would be as a free agent, the Braves decided to  include Heyward as the centerpiece of a blockbuster deal with the St. Louis Cardinals for Shelby Miller before the 2015 season.  Heyward was extremely valuable during this only season with the Cardinals, pairing his usually stellar defense with excellent offensive production.  All told, he was the 11th most valuable player (regardless of position) according to FanGraphs in 2015.  The below chart shows that Heyward was consistently above-average offensively during his time in Atlanta and St. Louis:


Due to his track record and his young age, Heyward commanded a massive deal after the 2015 season; he ultimately parlayed his performance into a hefty 8 years / $184M contract with the Chicago Cubs.

New Contract, New Town, Terrible Time

Yes, the Cubs won the World Series.  But on a personal level, the slugger’s first year with the team was a year to forget.  His offensive production dropped off a cliff, as shown in the below graph:


Heyward was mightily below-average at the plate last season; indeed, of the 394 players who registered over 150 plate appearances, Heyward ranked 321 in wOBA.  We might expect a precipitous decline like this from a hitter in the twilight of his career.  But for a player with his offensive track record, athleticism, and age to be so inept at the plate?  That is a massive deviation from expectation.

So, what happened at the plate last season?  To investigate, let’s examine a few groups of heat maps (courtesy of FanGraphs) to see if there are any glaring differences between 2015 and 2016.  First up is swing percentage; the top set of images is against left-handed pitchers, and the bottom set of images is against right-handed pitchers.

The charts lump all pitches together, so they would change if we subset by pitch type.  But in the aggregate, the graphs appear to show that Heyward swung at more inside pitches from left-handers and more up-in-the-zone pitches from right-handers last season than in 2015.

So, maybe Heyward was being slightly less selective.  How often did he make contact with these pitches?  Below is a comparison of Heyward’s contact percentage between 2015 and 2016, separated by pitcher handedness.

It’s tough to glean any glaring difference from the contact percentage graphs, as it appears that Heyward made a lot of contact in both 2015 and 2016.

But was it weak contact?  To answer that question, let’s look at his Isolated Power.  Isolated power is a measure of a hitter’s ability to hit for extra bases as opposed to singles, and I show the heat maps here as a proxy for hard contact.

You’ll notice a glaring difference in ISO between 2015 and 2016; compared to 2015, Heyward made significantly less hard contact against both lefties and righties.  Put all the heatmaps together, and it looks like Heyward made a great deal of weak contact in 2016.

But there’s one (huge) piece of the puzzle that we’re missing: luck!  Take a look at the following graph showing Heyward’s batting average on balls in play (BABIP) between 2010 and 2016:


As noted by FanGraphs, a high or low BABIP is not necessarily a sign of luck, but a BABIP that is substantially different from a player’s career mark usually is.  Heyward’s average BABIP from 2010-2015 was .305, and his BABIP in 2016 was .266.  Perhaps Heyward was simply unlucky.

This next point is key.  Think of player performance like a bell curve distribution, with some mean (i.e., the player’s true talent level) and some standard deviation of performance.  Any observed performance of that player is a random sampling within that player’s performance distribution.   We expect a player to perform at their true talent after a huge number of trials; yet over an arbitrary number of plate appearances (say, for a season), there is a chance that the player significantly over or under performs their true talent level.  This variation in observed performance is due to chance alone; Heyward simply had a year in the (very) bottom tail of his performance distribution.

Predicting Heyward’s 2017

So, given the above, what can we expect from Heyward offensively in 2017?  Has he completely lost his ability to hit?  Or should we expect a rebound season at the plate?

These days, publicly-available player predictions are easy to find.  Steamer, ZiPS, and PECOTA are three of the most well-known systems, and while each varies in complexity, they generally rely on (at least) weighted past performance, league performance, and age/athleticism.   For simplicity, we’ll just look at Steamer here.

And guess what?  Heyward’s projected wOBA for 2017 is .333.  Not .282 like his 2016 season, or league-average at roughly .310, but above-average at .333.   Why is the prediction so bullish on Heyward’s chances of a return to form in 2017?  The short answer: because that is what other players have done.

This is a key point about predictions: our best guess for Heyward’s offensive performance next season is based on comparable players.  In essence, there is nothing particularly special about Jason Heyward individually; we’d expect him to do what every other hitter with a similar profile has done before him.

To find comparable players, I built a database containing offensive statistics for every player-season from 1985 through 2016.   I subset the database to isolate those players with four consecutive years of offensive performance within +/- 0.02 of Heyward’s wOBA.  This means, essentially, that each of the players in the sample had three good years of offensive performance followed by one bad year.  We’re interested in how these players performed in the year following their bad year:


Weighting by plate appearances, we get a .325 wOBA across the entire sample of comparable players.  This is above league average; clearly, more often than not, the player returns to form after his bad year.

This is a good start, but this list includes athletes that are not comparable in age to Heyward.  The below table subsets the sample further to include only those players that are closer to Heyward on the age curve:



Aha!  Again weighting by plate appearances, these players posted a .337 wOBA in the year immediately following the bad performance.  By isolating those players that are on a similar portion of the age curve, we have come very close to replicating Heyward’s 2017 Steamer projection.  As we can now see, the projection systems predict that Heyward will bounce back precisely because that’s what comparable hitters tend to do.

There are rumblings of Heyward making major changes to his swing this offseason. However, when Heyward returns to his former self at the plate, don’t be too quick to attribute the success to the new swing.  Rather, remember that Heyward is due for a great deal of regression towards his true talent level, which means a bounce-back season is in order.  And what welcome news that must be for both Heyward and the Cubs!


Author: sittinglow80s

Former player, current student, curious fan

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