The new (and unimproved) Starlin Castro

It wasn't all that long ago that a bushy-haired, bright-eyed, 20-year old named Starlin Castro burst on to the scene on the North Side. Admittedly, he stole the hearts of many baseball fans, myself included, because he was a precocious hitting machine who played an exciting shortstop and even stole a few bases. At just 20, we couldn't collectively help but ask what kind of company he might eventually find himself given his propensity for hitting a baseball. Comps to Roberto Alomar and George Brett were thrown around, and while it was surely premature to think Starlin would end up in The Hall, we probably didn't think he'd be in the offensive company of Darwin Barney, Eric Young, Adeiny Hechavarria and Zack Cosart three years later.

So what the heck happened? As it turns out, that's not so easy to diagnose.

A quick glance at Castro's results over his four-year career shows some concerning issues, most of which are well known. He's never been prone to take a free base, as Starlin has drawn just 130 walks in 2617 plate appearances. Making his aversion to walks somewhat palatable is the fact that he's also managed to keep his strikeout rate in check, at least until it spiked in 2013. In his rookie season, his K/BB rate was an acceptable 2.45. While you'd expect to see growth from Castro, he's instead regressed in this aspect, as his 2013 K/BB ratio was an uglier 4.30. That puts him in some pretty unenviable company and further signals his lack of a solid approach at the plate. If he were hitting 25 home runs a season, I doubt anyone would mind, but as I'm sure you know, that's not the case.

His batting average has been his calling card, but his on-base percentage was surprising strong during his debut season. Unfortunately, it's trended down ever since. It was a pitiful .280 in 2013, a year in which his BABIP cratered. His first two seasons were supported by astronomical BABIPs of .346 and .344. Some regression was expected but he looked like the kind of guy who could sustain a high BABIP since he hits the ball on the ground at a high rate and has the foot speed to leg out some infield hits. His BABIP dropped to .290 last season, coinciding with his .245/.284/.347 triple-slash line.

And this is the point in which analysis can go wrong. We've found an indicator that we could easily point to and say, "hey, he was just unlucky, he'll be better going forward." After all, BABIP is the first place one would look to "test" his results. But that's perhaps a little lazy.

Instead, let's ask another question: why was his BABIP low?

My first thought was to track his batted ball profile over his brief and incomplete career:

Batted Ball
	GB%	LD%	FB%
2010	51.3	19.5	29.2
2011	48.6	20.1	31.1
2012	47.5	20.5	32.0
2013	50.7	19.9	29.4

Ok, so there's nothing compelling there. He hasn't given up a bunch of grounders and line drives for fly balls. Of course there's a little bit of fluctuation, but nothing that should shock us. This isn't the main reason behind his decline.

His swing data was my next stopping point. Let's take a look at that:

PITCHf/x Swing
	Swing%	O-Swing%	Z-Swing%
2010	46.9	33.7	60.4
2011	48.6	32.9	64.6
2012	49.6	35.2	64.3
2013	47.3	32.6	62.5

His overall swing rate hasn't changed in any kind of dramatic way. In fact, he swung at far fewer pitches outside the zone (O_Swing%) last year and got back in line with his successful 2010 and 2011 campaigns. He also swung at the most pitches in the zone of his career, another promising sign. He's swinging at fewer pitches outside the zone and more pitches inside the zone. That sounds good to me, but this doesn't explain his drop.

So I looked in one last place. Let's examine his contact data and see if we make any sense of this mess:

PITCHf/x Contact
	Contact%	O-Contact%	Z-Contact%
2010	86.1	74.9	92.4
2011	84.7	68.7	93.0
2012	83.0	66.4	92.4
2013	81.7	67.6	89.2

Whoa, there's something to this. Castro is swinging at fewer pitches out of the zone and more pitches in the zone, yet his overall contact rate has fallen. He whiffed at more pitches inside the zone in 2013 than ever before in an alarming way. He waited to get pitches over the plate before swinging, but Starlin just didn't hit them at the rate he has in the past. That seems counterintuitive and we should look for further evidence before we confirm that this isn't just some fluke.

Let's take a look at the metamorphosis of Starlin Castro by comparing his batting stance in 2010 to his stance from 2013.

2010

2013

Ok, we can see some clear differences here. Since his debut, he's opened his stance, squatted more and leveled the bat while moving his hands up and back. There's really nothing similar about his stances (ok, yeah, outside of the fact that he's in the same batter's box), signaling a total shift in his setup.

Now, let's take a look at his swings:

2010

2013

His swing in 2010 is very quiet. He gets his hands to the ball in a direct manner and it's a level, line-drive type of swing. Pay close attention to the small stride and small leg-kick. This swing is built for contact and line drives, just what you'd like to see from a guy like Castro as he's best served to put it in play and fly up the line.

His swing in 2013 has morphed into one with more power emphasis, as he has comparatively more loft in the swing. But again, notice the stride and leg-kick. It's much more pronounced than before. It's no secret that hitters with this type of swing will swing-and-miss more often as the leg-kick can make it tough to adjust to off-speed and breaking pitches. Add this to his open stance that makes it tougher to cover the outer half of the plate and it's no surprise that he's making less contact. And when he is making contact, it's often weaker unless he really squares up something on the inner half. Less firm contact and more weak contact would likely have a very real impact on his BABIP.

If it seems like this is a different Starlin Castro, it's because he's changed in a dramatic way. This seems to have had a profound impact on his results, and not in a good way. A 50-point drop in BABIP can signal some bad luck, yes, but sometimes you make your own luck, and in this case, Castro's shift to swinging for more power seems to have robbed him of his most valuable asset: quality contact. It's a trade off that most players are forced to consider, unless that player is Mike Trout. In Starlin's case, swinging for power is likely the wrong choice.

Keep an eye on his spring training at-bats to see if he's made further adjustments. With a bunch of talented infielders in the Cubs' minor league system, Starlin Castro needs to figure this out sooner rather than later.

*All statistics courtesy of FanGraphs

*GIF's courtesy of our own Jen Mac Ramos

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Jeff Wiser is a contributor to Beyond the Box Score and co-author of Inside the 'Zona, an analytical look at the Arizona Diamondbacks. He occasionally blogs about craft beer at BeerGraphs and you can follow him on Twitter @OutfieldGrass24.