The term ‘sophomore slump’ originated in educational circles to highlight the tendency for second-year college students to regress academically from their freshman year. The standard explanation argues that the unfettered excitement and adrenaline brought about by the new experiences of freshman year motivates pupils to feel more engaged in class and study harder. Unfortunately, this enthusiasm turns to a malaise by their second year, dragging down morale, work ethic and eventually academic performance.
Sophomore slump also gets used in sports to describe the difficulties that many players face transitioning from their rookie into their second seasons. While a decreased work ethic might be part of the cause, sports throws in an additional quirk with opponents that continually look to adapt to exploit weaknesses. So not only do second-year players need to maintain their work ethic, they must adapt with their competition.
Every MLB season features a multitude of sophomore players who regress significantly from their rookie seasons. 2017 is no different, headlined by seven players who probably wish they could turn the clock back 12 months (or 24 months in one case): Aledmys Diaz, Andrew Benintendi, Dansby Swanson, Keon Broxton, Kyle Schwarber, Ryan Schmipf and Trevor Story.
How the mighty have fallen
At this point last season most of the aforementioned players were riding high. Diaz was in the midst of a tremendous rookie season with St. Louis, while Benintendi and Swanson were having great minor league seasons and on the precipice of major league call-ups. Trevor Story had the best first week of any player ever, setting the record for most home runs in a team’s first six games of the season. Ryan Schimpf, after spending years toiling in the minors for the Blue Jays and Padres, broke out in a big way with San Diego. Kyle Schwarber, having ruptured his ACL in LCL in the second game of the 2016 season, smacked 16 home runs in 69 games in his 2015 rookie season.
In terms of aggregate numbers, the septet slugged their way to a .266 / .353 / .506 triple slash line in their rookie campaigns. Their .858 OPS led to a Weighted Runs Created Plus (wRC+) of 124, which means that their rookie offensive production was 24% better than league average. Expectations were high for each of the seven heading into the 2017 season.
But boy have they disappointed. Diaz, Swanson, Broxton, Schwarber and Schimpf were all demoted to the minors at one point or another, while Story has started losing at bats to backup Pat Valailka. Benitendi has performed the best of the bunch with a nearly average 97 wRC+, but has still disappointed relative to his 2016 numbers and the expectations heading into this season. All told, the group has managed a putrid .224 / .305 / .398 triple slash in 2017, with a 79 wRC+ (21% below league average).
Is poor plate discipline to blame?
While the aforementioned players are all different ages, have different pedigrees and bring vastly different approaches to the plate, I wanted to see if there were any commonalities in why this group was suffering from a prolonged sophomore slump.
The first place to look when discussing why relatively young players would start to struggle in their sophomore seasons is plate discipline. The thought is that as pitchers begin to adapt to a hitters’ tendencies, they become more adept at striking them out and avoiding walks.
However, the general plate discipline metrics of the seven hitters more or less stayed the same. The walk rate of the group went down from 10.8% to 9.9%, while the strikeout rate increased from 26.2% to 26.6%. In aggregate, the walk-to-strikeout ratio of the group went down from 0.45 to 0.40, which isn’t much of an overall change.
Swanson, Schwarber, Schimpf and Story maintained nearly identical numbers from season to season. With that said, there were some obvious divergences within the group. Andrew Benitendi dramatically increased his plate discipline year to year, while Aledmys Diaz and Keon Broxton saw dramatic decreases.
Based on four of the seven players in the group maintaining their plate discipline metrics, and Andrew Benintendi dramatically improving his, it’s safe to rule out increased strikeouts and or decreased walks as a primary factor in their regression.
Batted ball distribution
After dealing with what happens when the ball isn’t hit into the play, the next step is to evaluate what happens when contact is made. Although this is an oversimplification of things, consider line drives, flyballs and hard hit balls as good, and groundballs and infield flyballs as bad.
Now we’re getting somewhere. Five of the seven players experienced reductions in line drive rate, with average line drive rate decreasing from 19.4% to 18.5%. Average flyball rate went down significantly from 43.2% to 40.6%. And, most alarmingly, six of the seven players felt a drop in hard hit rate, with average hard hit rate going down significantly from 37.9% to 31.4%.
Moreover, the percentage of infield flyballs went up for six of the seven players, with the overall average moving from 9.8% to 11.2%. Infield flyballs are essentially the same as strikeouts in terms of providing zero offensive value, so a sharp increase in their prevalence is bad news for the hitter.
An across the board decrease in line drives, flyballs and overall hard hit balls paints a clear picture of diminished batted ball authority. With softer contact comes a lower batting average on balls in play (BABIP), which is exactly what happened to every player, with average BABIP going down from .323 to a decrepit .274.
BABIP, especially in samples of less than one season, can be very prone to luck-based fluctuations. While an aggregate 37.9% hard hit rate is good, it likely isn’t good enough to sustainability produce a .323 BABIP. Likewise, a .274 BABIP does not necessarily conflate with a 31.4% hard hit rate either, so there is some bad luck going around in the sophomore campaign. But any way you slice, the line drive and hard hit data clearly demonstrates reduced ability to square up the ball.
So what happened?
The next step is to evaluate why the batted ball authority of our seven sophomore slumpers went down so precipitously. Unfortunately this is a complicated question to answer and outside the purview of this post. However, my working yet unsubstantiated theory is that while the hitters’ basic plate discipline stats looked similar (strikeouts and walks), we’ll find that they get behind in more counts and swing at more bad pitches outside of the strike zone, leading to weaker contact. Stay tuned for a future post on the topic.