The reinvention of Jackie Bradley Jr.

The Boston Red Sox are considered to have one of the best outfields in all of baseball and that wouldn’t be possible without Jackie Bradley Jr. Before last season, he wasn’t much of an offensive threat and was only known for his defensive value. His excellent defense wasn’t awarded until just this past year as he was a recipient of a 2018 gold glove award. However, throughout his career, he has excelled at defense and especially in recent seasons. From 2016 to 2018 Bradley Jr. placed third among center fielders in UZR (Ultimate Zone Rating). UZR is the best defensive metric so far and is put to scale to that any defenders can be compared regardless of position. For Jackie, it’s been his defensive value that defined his career up until last season. Now, he poses as an offensive threat at the plate and is one of the most valuable assets to the Red Sox organization.

You can obviously see Jackie Bradley Jr.’s jump in performance by looking at his career stats. However, that doesn’t explain what caused the jump in performance. It was a cause and effect type scenario. He either made some sort of a change or maybe he just simply finally adjusted to the league, regardless, whatever the case may be, the effect was an increase in performance.

One variable that I was able to see as one of the “causes” was his average exit velocity. You can see below his career chart and how it took a rather large jump last season.

Data via Baseball Savant

Along with his average exit velocity, his barrel% also took a significant jump and his chart basically mirrored the one above. As I continued to explore his statcast measurements, I noticed his most significant jump, it was his hard hit%. Take a look for yourself, his season by season numbers were almost identical every year up until last year. I would definitely consider that to be a large jump in performance.

Data via Baseball Savant

Now you have seen the statcast numbers behind the increase in performance, specifically the batted ball measurements. This jump in average exit velocity, as well as hard hit%, definitely seems like a clear explanation to his jump in performance.

Batted ball measurements are not the only reason for Bradley Jr.’s jump in performance. It did play one of the biggest roles but there are a few other factors to be considered. Statistics that measure variables like plate discipline or the ability to make consistent contact also play a role in performance. However, when I took a look at those statistics not much had changed last season. His K% and BB% hadn’t made any sort of a noticeable change and his K% actually went up last season despite the jump in overall offensive performance. I took a deeper look into some of his other measurements that fell under this category and I did find a variable that contributed to his jump in offensive performance. Jackie Bradley Jr.’s Chase% took a noticeable dip last season meaning that he didn’t swing at as many pitches outside of the strike zone. Take a look for yourself below, it’s actually decreased the past two seasons.

Data via Baseball Savant

After evaluating his statcast measurements I contemplated as to if there were any other potential measurements that could explain his boost in performance. Obviously, I don’t have access to biomechanical data even though it would provide answers to so many questions that I have. So, instead I decided to take a look at his film from over the years to see if I could notice any sort of a change in mechanics. I compared his swing from the 2018 season side by side with his swing from the 2017 season. I was unable to take notice of any sort of major mechanical change but that doesn’t mean that one didn’t occur. There could be a change that I was unable to see from the footage that I compared. I was only able to compare his swing from the front facing (broadcast) view. A view from the side angle may show something different from the viewpoint that I had. None the less, I was unable to find any distinctive difference. Take a look for yourself and compare the two swings from each season. I believe that the load position is the best point in the swing for comparison on a still frame image. The image on the left is from the 2018 ALCS while the image on the right is from a 2017 regular season game.

Despite there not being any major changes, I did notice a few slight differences like the height of leg kick and his hand positioning. However, I believe the reason for that is the time that the photo was captured and not an actual change in mechanics. After coming to this conclusion, I realized that this is a rather odd scenario. Usually, when a player makes this sort of jump in offensive performance, it can be credited to a change in mechanics. However, this is clearly not the case with Jackie Bradley Jr. The statcast numbers do provide some sort of an explanation but what is the explanation behind the increase in those numbers. It seems the most logical conclusion is plate discipline. Last season he didn’t chase as many pitches outside of the strike zone as he had in the past. He is improving as a hitter with age and for the Red Sox, he is now a very valuable asset to their organization.