Xander Bogaerts and the Uneven Road to Success

We haven’t spoken about Xander Bogaerts at length in these digital pages for some time, so let’s remedy that situation. It seems like a good time to check in on the young shortstop’s development as a major-league hitter: Bogaerts is posting a wRC+ north of 100 in the first two months of the season, and he’s also almost cut his strikeout rate in half compared to last year. There’s also this group, which is an interesting subset of players, of which Boston’s shortstop is the leader — hitters with the highest increase in batted balls to the opposite field this season over last season:

Though it’s still perhaps a little early to be putting a ton of confidence in these numbers, changes as large as these in a hitter’s opposite-field tendencies merit attention. Opposite-field approach is often a good place to look when searching for a reason behind a change in type of production, and, given the drop in Bogaert’s ISO numbers from last year — .123 in 2014 vs. .106 this year — plus the fact that we’re over the ISO stabilization point, it’s one of the spots we’re going to focus on.

To begin with, we’ll talk about Bogaert’s previous vulnerabilities. He struck out just over 23% of the time in 2014, with 30% of those strikeouts coming on sliders. Take a look at his overall strikeout heat map for 2014 (courtesy of Baseball Savant), and you can probably pick out the trouble spot:

As many hitters do, Bogaerts struggled with the slider (and pitches in general) low and away last season. As we can see, he also showed a general weakness in pitches down in the zone. That’s now the book on him, in fact: 59.3% of pitches he’s seen in 2015 have been in the bottom third of the strike zone or lower, compared to 53.4% in 2014. Many hitters would adjust by trying to lay off those pitches, especially the ones out of the zone, tightening up their swing area to make themselves less prone to striking out.

Not Bogaerts. He’s taken the opposite tack; he’s adjusted by starting to hit those pitches, even off the plate. Here are his plate discipline numbers between last year and this year (I’ve omitted 2013 because he only played 18 games):

Season	O-Swing%	Z-Swing%	Swing%	O-Contact%	Z-Contact%	Contact%
2014	28.5%	60.5%	44.8%	59.2%	86.4%	77.9%
2015	33.3%	62.2%	47.6%	72.4%	88.9%	83.1%

His O-Contact% has taken an especially huge jump, coupled with a higher tendency to swing at pitches out of the zone. He’s now swinging at pitches he struggled against far more often in 2015 than last year, and he’s hitting them at a much higher rate. In a way, you have to admire this strategy; he’s taken the road less traveled, and is confronting the areas of his previous struggles head-on. Let’s look at his swing rates in different parts of the zone between last year and this year — pay special attention to the area just below the bottom of the strike zone:

Those areas below the zone have seen an increase of between 5-15 percentage points in swing rate this season, and he’s now swinging at low pitches out of the zone almost 50% of the time. If he wasn’t making so much more contact, this would probably be seen as a disastrous development; however, as we’ve seen in his plate-discipline stats, he is making more contact — significantly more in some cases. So what is he doing with that contact?

This is where we return to our original graphic about his increased opposite-field tendencies. We know a few things about hitting to the opposite field. First, it is very difficult to do consistently with a lot of power. Second, players often see a little jump in batting average when they move toward hitting to the opposite field more often.

And, in case you couldn’t guess what I’m getting at, Bogaerts has shown both of those developments in his batting line this year. He’s going the other way more often, and he’s hitting singles more often. Overall, it has made him a more productive offensive player, but it has also done what pitchers intended to do by throwing him pitches away and out of the zone — take away his power. Look at his spray chart this year to see his hit tendencies:

Source: FanGraphs

That blob of singles to right field? They are almost entirely ground ball singles. By swinging at so many pitches low and out of the zone, he’s hitting a lot more grounders this year (48.2% in 2015 vs. 38.1% last year), effectively sapping his ability to hit for extra bases. He has just two extra-base hits to the opposite field this season, and they’re both triples. Triples are often pretty flukey — here’s one of them this year:

This is where we start to discuss the nature of adjustments players make. Bogaerts obviously has realized how he’s being pitched, and he’s made an adjustment, one which has resulted in less power and a few more singles than last year. Whether that adjustment will keep resulting in these sorts of outcomes remains to be seen — it’s still too early to know for sure. However, this is obviously an overall positive change he’s made; it may not be the final, ideal version of Bogaerts, but it is a better one than before. Combined with his above-average defensive play at shortstop this year, he’s now one of the best players on his team, and he’s currently a top-five shortstop in the major leagues.

Bogaerts has made the type of adjustment that may not cause a readjustment from pitchers: he’s swinging at the pitches they want him to swing at. In an ideal world, we would probably like him to not swing at those pitches out of the strike zone at all, force pitchers to come back into the zone, and look for pitches to drive. He’s not there yet, however, and this particular adjustment might just be one rung on the ladder to his final form. In the glimmer of a future Bogaerts in our minds’ eye, we probably do not see a low-power singles hitter. This latest adjustment shouldn’t change that.

We can forget, in this era of Bryce Harper and Mike Trout, that development curves aren’t the same, and players take longer than others to start showing the potential we’ve been told about. Bogaerts is still only 22 years old, and it may seem like he’s been in the league for awhile. He hasn’t; he’s still learning, still adjusting, and showing that perhaps his development might be a case of the incremental instead of the immediate breakout — the click. One thing we know for sure: it’s endlessly fascinating to watch a young player continually adjust to the highest level of play. Sometimes those adjustments don’t look like you expect them to: often they’re a baby step forward, or even a step sideways. The most important aspect of them? That they keep happening.