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Xander Bogaerts has started hitting sliders

Xander Bogaerts produced at the plate in 2015, but how did he fare against sliders?

Kim Klement-USA TODAY Sports

Last offseason I wrote an article for Fansided’s ‘Call to the Pen’ on Boston Red Sox SS Xander Bogaerts’ inability to deal with sliders. At that time my writing was…awful. I don’t shudder in disgust quite as much upon re-reading more recent articles — as good a benchmark for improvement as any. But, if you can stomach my past writing long enough to find the main point, it was this: Bogaerts’ strife against sliders played a key role in his 2014 offensive struggles.

If you can remember back loooong ago to the year 2014, the young shortstop was rendered largely ineffective by that very pitch. You can probably glean that information from his .147 BA and .028 ISO against sliders. That, and the fact that Bogaerts was the least effective hitter against sliders in all of Major League Baseball that year, according to FanGraphs’ pitch type linear weights. Well, maybe that isn’t quite fair. While owning a wSL of -12.2 clearly highlights the lack of success he had against the pitch, ‘least effective in all of Major League Baseball’ is probably a little harsh. The more attempts you get against a pitch the greater the chance for you to look bad in the eyes of this specific metric. There is wSL/C, which is an average and better to use when comparing players, but both say the same thing. Bogaerts was awful against sliders, and it was made worse because pitchers exploited the weakness.

In fact, according to a column written by Peter Abraham of the Boston Globe, this is something opposing pitchers noticed:

"He can’t hit a slider," said a Yankees pitcher, who asked not to be identified after last weekend’s series against the Sox. "Then when he starts to look for the slider you can get a fastball by him. He’s not the same hitter he was before."

Then came 2015, and something changed. Bogaerts looked good at the plate overall, and in comparison to all the shortstops in Major League Baseball who came to the dish at least 250 times, he was the fifth best (in terms of wRC+). Oh yeah, and he noticeably started having success against sliders. Bogaerts doubled his average (.283), tripled his ISO (.080), and saw his progress generalized by an above average 2.3 wSL. This was thanks to a new approach—he started taking the ball to the opposite field more often:

As you can see, there was a shift in his spray chart toward right field, which made an immediate impact and is likely derived from where exactly he is being pitched. The trend for pitchers, especially righties, against Bogaerts is to throw their sliders on the outer portion of the plate. Nothing really changed from 2014 to 2015 in that department, meaning that Bogaerts' adjustment was just to hit the pitch where it was thrown. It was as simple as that.

Well, simple in the sense that one can understand why he started to go the other way. But when you look at how he combined this opposite field approach with a 57.32 percent GB/BIP (an alarmingly-high 17.32 percent increase from 2014), it gets intriguing. Bogaerts’ improvement in dealing with that wily devil known as the slider came, in large part, from opting for contact over power.

As Owen Wilson of FanGraphs describes, Xander hit the pitch where the pitcher wanted him to hit it. Though Wilson was speaking of his game overall, the point remains—by going the opposite way it is harder for him to garner as much power, and, from the pitcher's perspective, throwing a slider away that is given up for a single is much more enticing than a slider given up for extra bases. So, in a way, Bogaerts sacrificed the potential for more power with the willingness to hit more singles. By putting the ball on the ground, as opposed to driving the ball. Finding the hole in the infield, rather than the gaps in the outfield. That might seem like a poor decision for a hitter with more developed power. Yet for a hitter, like Bogaerts, with speed and who is still in the process of developing power, it’s a pretty good gamble.

I say that, but it seems odd to sit here and act like the 23 year old should go from noticeable struggles with sliders to a power hitting/slider-destroying phenom relatively overnight, anyway. That’s just not realistic. The point is that you can see the adjustments he made. You can see one of the future stars of Major League Baseball making the changes to MLB-level pitching he needs to, and it only alludes to his ability to either build on these fixes going forward and/or adjust to new challenges pitchers (quite literally) throw at him.

He didn’t demolish sliders last season, he learned to deal with them. Well, I mean he did demolish this slider, but that was to his pull-side:

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Regardless, Bogaerts took a major step forward by appearing to close a glaring hole in his game. Now that he has established an ability to put the pitch in play all over the field, the next logical step is to begin adding power. Whether that happens this upcoming season or three years down the road, who knows. What I do know is that Bogaerts found a solution to his struggles against sliders, and having success on a pitch he saw more than double any other offspeed pitch was crucial to his turnaround in 2015.

. . .

Shawn Brody is a contributor for Beyond the Box Score as well as a sophomore pitcher at Howard Payne University majoring in Business Management. If you would like to get a hold of him, please feel free to email him at or follow him on Twitter @ShawnBrody.