The Evolution of Jackie Bradley Jr.

Coming into the 2016 season, Red Sox fans did not know whether their center fielder would be the hitter who didn’t look capable of sticking in the majors, or one of the hottest hitters in baseball. Nearly a month and a half through the season, the Boston offense is humming along and JBJ looks like Boston’s savior. Ian York uses heat maps and his his unique charts to illustrate the evolution of Jackie Bradley Jr. as a professional hitter.

Jackie Bradley Jr. was a very promising prospect, with scouts salivating over both his offense and defense in the minors. After a year and a half in the majors, though, he was starting to look like a classic AAAA player whose offense couldn’t hold up to major-league pitching: his OPS in 2014 was an abysmal .531, and through his first 24 games in 2015 it sat at an even worse .426.

In his 87 games since then, Bradley has hit .310/.368/.609/.977.  Eighty-seven games start to be a decent sample size. Admittedly, Bradley’s 2015 numbers were the product of a smoking-hot 25-game streak bracketed by ice-cold periods, but 37 games into 2016 Bradley has been consistent, as his 21-game hitting streak shows.

How has Bradley changed his approach over the past three seasons? For one, he has expanded the region in the strike zone in which he can hit well. Here we show Bradley’s total bases per pitch, for each of the past three years, broken down by pitch type and region around the strike zone. The distribution of the pitches he saw is also shown as contour plots in the background:

In 2014, Bradley had very few hits, and almost all were on pitches near the bottom of the strike zone. Unsurprisingly, most of the fastballs he saw were in the upper third of the zone. What’s more, pitchers didn’t bother throwing much other than fastballs to him (67.6% of pitches from left-handed pitchers; 65.5% from right-handers), since he showed he was pretty much helpless against them.

In 2015, Bradley showed that he could hit fastballs, including inside pitches and pitches in the upper half of the zone. He was still somewhat shaky against breaking pitches, though he was much better than in 2014, and right-handed pitchers increased their share of those pitches from 20.2% to 25.0%, reducing their fastballs by about the same amount.

So far in 2016, Bradley has hit well against fastballs located anywhere in the zone, and has greatly improved his hitting against breaking balls. Right-handed pitchers have increased their use of breaking pitches still more this year (to 28.2%), but it wouldn’t be surprising to see that drop again in the rest of the year.

Bradley has become more aggressive this year, with his first-pitch swing percentage going from 25.5% in 2015 to 31.0% in 2016. League average is 28.1% this year, and was 28.9% in 2015, so Bradley has gone from a relatively cautious first-pitch swinger to one who is more aggressive than average.

On the other hand, he has become more picky about the location of pitches he swings at. In this chart, Bradley’s tendency to swing at pitches is compared to that of all left-handed batters. Regions where he is less likely to swing than the average batter are blue; those where he is more likely to swing are red:

In most zones, the colors are fairly muted, showing that although he is less likely to swing the difference is small. However, he has shown that he is significantly less likely to swing at offspeed pitches outside the strike zone, which were a particular weakness of his in 2014 and (to a lesser extent) in 2015.

Overall, Bradley has become a more aggressive hitter while also becoming more selective about what he swings at, and making harder contact over a wider area in the zone, and doing so while pitchers are trying to adapt to his new plate coverage. Bradley may not be a .980-OPS player over the rest of the season, but we are seeing enough to think he can easily be an over-.800-level batter, which would have been a wildly optimistic hope in July of last year. This powerful hitter (and elite defender) is the Bradley we had all hoped to see over the past two years.

Ian York uses the PITCHf/x to monitor the strike zone, highlights great performances, monitors league-wide trends and tracks the performances of some interesting young hitters.

Follow Ian on Twitter @iayork.

All data compiled from PITCHf/x and

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Ian is an immunologist and virologist who lives in Atlanta with his wife and two sons. Most of his time is spent driving his kids to baseball and soccer games, during which he indoctrinates his children on the glories of Pedro Martinez, the many virtues of the Montreal Expos, and other important information.