Guest Post: The Continuing Education of Starlin Castro

The following is a guest post from AJ Walsh.  You may know AJ from the Cubs blog 'Goat Riders of the Apocalypse".  He has also written for Major League Trade Rumors.  We are pleased to have him contribute this excellent article on the ever evolvng Starlin Castro.  You can follow AJ on Twitter @ajwalsh08.


Starlin Castro's offensive output has been falling since Opening Day. By month, his OPS is down from .784 in April — which is already almost not that good — to .763, to .711, to .687 in July. So much for Anthony Rizzo helping him out over the past 31 days.

That said, I think Castro is improving his core skill set as a hitter this year, and love what I see in a few key trends. How can this be when his OPS has simultaneously fallen from decent to, uhh, no thank you? Let's look at five key stats, all viewable in graph form here: (Thanks, Fangraphs!)

1. ISO

This is the biggie. For those unfamiliar, ISO measures raw power by removing singles from a hitter's slugging percentage and isolating extra-base hits. To calculate ISO, one subtracts AVG from SLG, leaving only the extra bases earned with the bat. The most powerful hitters can approach .300; for example, David Ortiz is batting .316 this season, and slugging .609, giving him the league's second-best ISO at .294. Hitters without power tend to be at or below .100; Ichiro's .095 ISO this year is a good example.

So where is Castro on this scale? In short, he's climbing the ladder. His ISOs this season by month: .100, .148, .145, .173. And to be even more selective about my small sample, since the break he's at .203. Like I said, climbing. This is especially good to see because he put up a .108 in his rookie year, and a .125 in 2011. And if he's going to be a formidable hitter he needs power. I'd love to see him maintain that .200-ish ISO over the balance of 2012, as I'm sure would the guys in the Cub front office and the other fans in the stands.

2. K and BB

These two we can discuss at the same time; let's start with strikeouts. When Castro was only putting up .108 in ISO, it was important that he cover the plate well and frequently put the ball in play to maintain his offensive value. Fortunately he was able to achieve this in 2010, putting up a 14% K-rate on the year, just under Derek Jeter (Juan Pierre was just above 6%, but most of the league leaders were between 9% and 14%). That rate went down a hair in 2011, before climbing this year — through June 16 (an admittedly arbitrary date), his rate was up above 18%, with 51 Ks in 281 PAs.

You might think it a consequence of his adding power — except that over the past month and change the trend has reversed. Maybe it's too small a sample size to take anything from, but since that game on June 16 Castro's K rate is down to 11.6%, with just 18 Ks in 155 PAs.

Meanwhile, his walk rate — which fell from 5.7% in 2010, to 4.9% in '11, to 3.7% over 2012 — is up to 8.3% over those same past 155 PAs. Both encouraging stuff.

3. BABIP and GB%

There's never been any reason to worry about Castro's BABIP; he was up near .350 for about 1,000 PAs to start his pro career. But over the first four months of 2012: .380, .333, .310, .238. A .238 in July! That's bad! He was above .333 in every month in 2011 save one (.305), and did put up a couple of .270s in his rookie year. But .238! It stands out.

The culprit appears to be a result in batted balls, with Castro's groundball rate climbing dramatically over the last several weeks (refer back to the graphs at Fangraphs, unfortunately I can't find this in number form split up into months). I don't know if that's a random thing? I'm not that smart. But maybe it is? On the full year, anyway, Castro's batted ball types for 2012 are essentially identical to 2012. So maybe he's just been unlucky this month — which would explain the decreased output in terms of OPS, despite the fact that his power is increasing and his K/BB numbers are both moving in the right direction.

Those are, I think, the numbers behind the final output statistics that matter more. I hope you agree that there are some encouraging signs here, despite the fact that Castro's OPS has been in decline since day one of this season.

Filed under: Analysis, Guest Post


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  • fb_avatar

    Great points here....very informative for the people who like to rip on players without seeing the deeper point of view which most of us here do.

    Side note: I think one guy we should really watch out for is Welington Castillo. He always seems so close to breaking out and in my eyes he just needs to get comfortable. The guy can rake. I think we'll be surprised at his production.

  • Nice analysis, AJ. I think we're seeing a budding superstar here -- an above average defensive SS who will hit for average and power, then if he adds OBP skills, which I think he will, he'll be a monster.

  • One of the interesting things about Castro is that most of his power seems to be to dead CF. There were also 2-3 would be HRs in April that were knocked down as well, and they were to CF. The legit CF power makes me wonder whether, as he gets more experienced, he can hit the ball out to LF a bit more.

  • In reply to SVAZCUB:

    He's still learning to turn on pitches. When he does, he'll be a 25 HR guy.

  • In reply to John Arguello:

    You don't really hear that too often...hoping a guy 'learns' to turn on pitches. He can generate some impressive bat speed when he wants to as well. His LF HR's are generally line drive that probably never get higher than the bleachers.

  • In reply to Cameron Macpherson:

    I always remember that being the case with Ryne Sandberg and though, they're different players, sometimes Castro reminds me of him. Sandberg had the same kind of fluid, effortless athleticism and the ability to make contact and take the ball back up the middle (and the bad habit of swinging at low and outside pitches from time to time)

  • meant to say "knocked down by the wind" in last post

  • Great article. His average drop is troubling, but I get the idea you're right and we're seeing the birth of a power hitter here. You can almost see the gears turning while he's thinking in between pitches. I wouldn't be at all surprised if he finishes the year with 20+ homeruns.

    Maybe he's trying to hit for power by pulling more pitches. That would explain the increased groundball % since trying to pull everything often leads RH hitters to turn over on the ball and ground it to the left hand side. Probably get an idea if this is true by comparing his spray chart over his last 155 plate appearances and seeing if it's more left side heavy than the rest of his career..

  • In reply to Carne Harris:

    I think it was just more of a bad funk. He was trying to take more pitches, and was fighting his instincts too much and just swinging at the wrong pitches at the wrong time. He has started to hit better though. I would like to see more pitches put down the RF line, instant double. I do hope that he remains in the 2 hole moving forward though, regardless of his eventual power development, it's the right spot for him.

  • In reply to Cameron Macpherson:

    You can tell someone's gotten in his ear about the Cubs' philosophy of waiting for your pitch, and that he's getting out of his comfort zone a bit and trying to do that. Funny thing is, before reading this, I would have thought for sure his SO % was way up, all those Dunston-esque down and away sliders he's been swinging at lately.

  • In reply to Carne Harris:

    I've noticed a lot of groundballs as well. He went through a streak where he kept rolling his wrists over and grounding weakly to SS. Glad that seems to be over for now.

  • fb_avatar

    Nice post, AJ. Can we get a follow up on this after the season ends?

  • In reply to Just Win:


  • Great article! Never fully understood what ISO was all about. Every time I come to the Cubs Den I learn something new.

    What do you think the front office will do with Castro's contract in the off season? He is arb-eligible, right? You think they'll try do hook him up long term?

  • In reply to Cub Fan Dan:

    I think there's a chance they try to lock him up with a long term team friendly deal that gives him some security and maybe buys up a free agent year or two.

  • Great post AJ. Really enjoyed it and I learned something too.

  • fb_avatar

    I think Castro will develop into a 20 plus home run threat.. I just hope his average doesn't take a huge hit.. Can't wait to c what are infield looks like in 2 years.. Hopefully Baez Castro.. No idea were we can put Lake..

  • fb_avatar

    Good stuff AJ. Thanks for posting.

  • Thanks everyone for your feedback. Great community you have here at CubsDen, John.

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