Why is Starlin Castro struggling?

Castro has a career-low .235 BA this season. (Copyright: ESPN)

Castro has a career-low .232 BA this season. (Copyright: ESPN)

It’s not often that we talk about the decline of a 23-year-old baseball player; most players don’t even reach the big leagues until they’re at least 24 years old. But allow me to ask: what in the world has happened to Starlin Castro?

Since hitting .300/.347/.408 as a 20-year-old rookie in 2010, Castro’s on-base percentage has decreased in every one of his three and a half seasons as the Cubs shortstop; it currently sits at .266. Moreover, the steady increase in power we witnessed over the course of Castro’s first three seasons has seemingly disappeared, with his isolated power falling from .147 last season to .091 this season.

Is Castro’s decline in production simply attributable to bad luck, or is something else at play here? As I’ll attempt to show in this blog post, both are probably true.

Like his OBP, Castro’s batting average on balls in play has decreased each season, from .346 in 2010, .344 in 2011 and .315 in 2012 to .277 this season. Is this all due to a regression in luck? Yes and no.  Castro’s line drive percentage actually increased from 19.5% in 2010 to 20.1% in 2011 and 20.5% in 2012 before falling to 17.8% thus far this season. Line drives, as we know, are more likely to result in hits than other batted ball types. However, Castro appears to be at least somewhat a victim of bad luck, as his BABIP in 2011 and 2012 decreased despite an increase in line drives.

On the other hand, Castro is hitting more fly balls and fewer ground balls now than he did as a rookie. In 2010, his GB/FB ratio was 1.76; in 312 plate appearances this season, it’s 1.39. This is significant because we also know that fly balls typically result in outs more often than ground balls. Adding to this problem is the fact that Castro is only hitting home runs on 3.6% of his fly balls.

As Dave Cameron pointed out, Castro’s contact rate has also declined. According to Baseball Info Solutions, Castro made contact on 91.8% of pitches inside the zone and 75.3% of pitches outside the zone in 2010; up until this season, Castro’s contact inside the zone has remained relatively constant, but his contact outside the zone has fallen to 71.2% in 2011 and 2012 and 70.5% in 2013.

Pitchers have noticed this downward trend: the percentage of pitches Castro has seen inside the zone has fallen from 47.6% in 2010 to 45.0% in 2013. Castro is making less contact on pitches outside the zone, so pitchers are smartly giving him more pitches outside the zone. Compounding this problem is the fact that Castro does not take many walks.

It should be noted, though, that data from PITCHf/x tell a slightly different story. The pitch tracking system agrees with BIS’ information on Castro’s declining contact rate from 2010 to 2012, which we can confidently say is almost entirely based on his declining rate of contact outside the zone. According to PITCHf/x, however, Castro’s rate of contact outside the zone has actually increased from last season (66.4%) to this season (67.7%). Both systems show a drop in Castro’s contact inside the zone this season, but PITCHf/x shows the drop to be more pronounced—from 92.4% in 2012 to 88.7% in 2013. Additionally, PITCHf/x shows less of a reduction in the percentage of pitches Castro sees inside the zone, from 49.6% in 2010 as 49.4% in 2013.

I’m not a sabermetrics wizard, but what I think we can glean from this information is that Castro’s sudden decline from last season to this season can at least partially be attributed to a fluky, small-sample-size drop in his rate of contact inside the zone—which is most likely the cause of his line drive rate—while his steady year-to-year drop in offensive production can be seen as a partial result of his decreasing contact rate outside the zone, a decreasing ground ball rate and an increasing fly ball rate.

Castro should be expected to improve over the rest of this season, but his falling contact rate is something to keep an eye on; as a guy who doesn’t take many walks, much of Castro’s value is tied to his ability to make contact. Castro’s seven-year, $60 million contract is pretty favorable for the Cubs, but if Castro doesn’t increase his power to offset the decline in his contact rate, I wouldn’t blame fans for beginning to be a little concerned.

*Unless otherwise noted, statistics used in this piece were reported by FanGraphs and as of June 21, 2013.

_______________________

Dan Edwards is a recent graduate of the University of Iowa in Economics/Finance. Currently, Dan is a scouting intern at Perfect Game USA, where he assists with tournaments and showcases across the country.

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