The Evolution of Xander Bogaerts

Since dominating the Dominican Summer League as a 17-year-old shortstop, Xander Bogaerts has been considered one of the elite young talents in the game, heralded for his on-base ability, and specifically his power.  After being promoted to start the 2011 season in Greenville, the Aruban native continued to rake, proving his skills at every rung of the organizational ladder.  At each full-season minor league level, Bogaerts never ran a wOBA below .366, and his lowest ISO was a very respectable .169.  It seemed as if he were destined to inherit the throne left vacant in Boston since Nomar Garciaparra departed in 2004; fans drooled over his future as the Red Sox’s franchise cornerstone, anchoring the heart of the Boston lineup while playing a premium defensive position.

On August 19, 2013, with Stephen Drew mired in a slump and the Sox struggling, Bogaerts was promoted from Pawtucket and joined the team in San Francisco, thus beginning his tenure in Boston.  Bogaerts appeared in 18 games down the stretch, hitting only 1 home run and watching his K% balloon to 26%.  However, his struggles were mostly ignored as the team wrapped up the division, and all concerns were quieted by the maturity he demonstrated after being inserted into the Sox’ starting lineup on baseball’s biggest stage, as evidenced by his .386 wOBA during the postseason run culminating with a title.  At the tender age of 20, Xander Bogaerts was a World Series champion, appearing poised for a Rookie of the Year campaign in 2014.

Unfortunately, Bogaerts failed to meet expectations in 2014, posting his worst season as a professional by far.  After a hot start, he collapsed in the second half.  He continued to strike out in nearly 25% of his plate appearances, his 6.6 BB% was a career worst at the time, and he finished with a disappointing 82 wRC+.  Bogaerts’s struggles were driven by his inability to hit right-handed pitching, as he posted a measly .105 ISO against righties coupled with a 71 wRC+.  The following image should help to explain the decline:

After getting ahead in the count, righties attacked Bogaerts down and away, leading him to chase breaking balls and expand the strike zone.  In fact, on a per-pitch basis, the rookie shortstop was the fifth-worst hitter in baseball against the slider.  With his confidence shattered after a poor performance at the plate along with Boston’s decision to sign Stephen Drew midseason, outsiders questioned whether Bogaerts could recover from his prolonged slump, while some predicted that he would be the next big prospect to bust.

After admitting that 2014 was probably the “toughest season [he] ever had,” Bogaerts entered 2015 once again as Boston’s starting shortstop, hoping to recapture the stroke that propelled him to the big leagues so rapidly.  Although he collected a Silver Slugger and seemingly accomplished his goal, Bogaerts exhibited a vastly different approach, one in stark contrast with his minor-league track record.  While he retained his high on-base ability, rather than selectively punishing mistakes, Bogaerts became a more restless slap hitter, sacrificing power in exchange for contact.  He boosted his Swing% by almost four points, offering at nearly half of the pitches he seen, but his ISO fell to a career worst .101.  This change can be attributed to his increased willingness to use the entire field; Bogaerts boosted his Oppo% by 13 points but showed nearly no power when going to right field as evidenced by a Hard% of only 14.5.  He also become an above average hitter on a per-pitch basis when challenged with sliders, improving upon perhaps what was his biggest weakness.

This more aggressive approach resulted in a significant drop in Bogaerts’s K%, coupled with a smaller decline in his BB%.  He finished the year with a much-improved 109 wRC+, certainly playable when coupled with league-average defense at shortstop, yet he left much to be desired in the minds of talent evaluators around baseball.  Rather than demonstrating the power he had exhibited throughout his minor-league career, Bogaerts instead resembled a weak middle infielder.  Once destined for stardom, Bogaerts had been relegated to an average shortstop, definitely a valuable piece on a contending team, but not the player many had projected him to be.

Now over 40 games into the regular season, despite capturing success in 2015, rather than settling, it appears that Bogaerts has once again evolved.  A quick glance at his numbers may suggest his improved offensive performance can be chalked up to luck, as evidenced by his high BABIP, but a deeper look at his underlying peripherals indicates that Bogaerts may have once again altered his approach at the plate.  First, he is proving that the decrease in K% is legitimate; Bogaerts is once again running a strikeout rate below 16%, nearly five points better than league average.  This year, it also appears that he has developed better command of the strike zone, as the has cut down his swing rate while boosting his BB%, both to nearly league-average levels.  More important than these, however, may be the reemergence of Bogaerts’s power.  Through 40 games, Bogaerts is running an ISO of .157, a level that he never once reached during his miserable 2015 season.

Unlike other unsustainable power surges, it seems as if Bogaerts’s may be viable.  His HR/FB has risen by nearly six percentage points, yet it still falls below the league average.  Statcast also seems to confirm our findings, as Bogaerts’s average exit velocity has risen by three miles per hour since the end of last season, although this data is still relatively new and cannot be considered a perfectly reliable indicator of future performance.  The majority of Bogaerts’s damage this season has come to the pull side, as his wRC+ has jumped by almost 100 points, and it seems as if he is making a concentrated effort to elevate more of the balls that he hits to left, as his FB% to the pull side has increased by nearly four points.  His bloated wRC+ will almost certainly fall, as a 44.4% HR/FB ratio to left field is absolutely ridiculous, but Bogaerts’s new offensive approach suits him well.

As seen in the table, Bogaerts is also demonstrating more power going the other way, and although his solid contact has still not resulted in any home runs to right field, the singles of 2015 have transformed into doubles this season.  Although he still sees the same number of percentage of pitches in the strike zone, it seems as if pitchers are approaching Bogaerts with more trepidation because of his newfound power, as he is seeing fewer fastballs this season than at any point during his major-league career.

The projections are a bit skeptical, as they forecast a fall in both BABIP and ISO, but if Bogaerts is able to maintain his current level of production, or really anything near it, 2016 will be his most successful season in the major leagues, by far.  He has undergone a major transformation at the plate, yet he has essentially reverted to the hitter he was as a prospect shooting through the minor leagues.  The strikeout-prone 2014 Xander Bogaerts gave way to the slap-hitter 2015 version, which then evolved into the more selective and powerful current manifestation of the young shortstop.  Perhaps most intimidating, however, is the fact that Bogaerts remains only 23 years old, and his evolution may not be complete.  Overshadowed prior to this season by the likes of Carlos Correa, Francisco Lindor, and Addison Russell, Xander Bogaerts appears set on mashing his way back into the conversation as the best young shortstop in baseball.