Which small sample breakouts are for real?

I’ve been working on a few things that are taking longer than anticipated, so I figured I’d try a fun little exercise this week. As you know, I’m a big believer in the combination of stats and scouting, having attended the MLB Scouting Bureau’s Scout Development Program last fall. Scouting can provide insight into things that numbers alone can’t.

Today, I thought I’d use more subjective means to try and evaluate pitchers who are performing well in 2010 but who have no previous track record of such performance. Essentially, I’ll look at 10 pitchers and try to decide if their 2010 strikeout rate success is sustainable using PITCHf/x and other relevant data. At the end of the year, I think it’ll be very interesting to go back and see how accurate these end up being.

Projection systems take a very formulaic approach to predicting the future, taking many years worth of data into account and regressing everyone to the league mean. This works very well on the whole, but some guys will get missed in the shuffle, and I don’t believe that everyone should be regressed to league average. Some players change in significant ways, and projection systems aren’t particularly adept at identifying these guys. The point of this exercise is to try and do just that.

For purposes of comparison, I’ll use Oliver’s rest-of-season projections and come up with my own rest-of-season predictions so that we have some way of testing this at year’s end. Please take my predictions with a grain of salt, though. I’m putting a precise number to it for the purposes of end-of-season testing, but they’re mostly just coming off the top of my head, a rough estimation of how I feel about a player. The general point is more important than the precise number.

Now, onto the players.

*Credit to TexasLeaguers.com for the PITCHf/x graphs.

Clay Hensley

IP: 27.2
K/9: 11.39
Previous career high K/9: 6.00




Hensley was a starter for most of his career and has never posted a K/9 above 6.00. This year, though, he’s dominating out of the Marlins pen and could be next in line for saves behind Leo Nunez. I’m definitely buying into Hensley based on a few factors, the biggest being his improved stuff. His breaking ball (which may or may not be two different pitches) is getting terrific movement with a wide range to keep hitters guessing. He’s also reversed the usage of his curveball-like breaking balls and slider-like breaking balls, using the curve more, which generates more swings-and-misses. His changeup is being used more often and is getting more sink.

Combine this with Hensley’s full-time move to the bullpen and pitching in Florida (which inflates Ks by 10.1 percent), I wouldn’t have a problem predicting Hensley to strike out at least a batter per inning the rest of the way.

Verdict: Largely sustain
Oliver ROS K/9 Projection: 6.3

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  1. Mike Podhorzer said...

    Great stuff Derek. I have another pitcher request- James Shields. 8.9 K/9 vs previous career high of 7.7 and just 6.8 last year. When I’ve watched him pitch, it appeared his fastball velocity was much higher as I didn’t ever recall him touching the mid-90’s in the past. Sure enough, his average velocity is up a full mile per hour. I would figure that would make his change-up that much more devastating.

    Unfortunately, his opposition contact rate and swinging strike percentage are actually down and at career worsts. So though his stuff appears better to my eye, the results aside from his strikeout rate have been worse, which is confounding. Analyze away!

  2. Huh? said...

    You included Jesse Chavez in a column about pitchers who are performing well in 2010.  I am confused.

  3. Josh said...

    I’m very interested in this type of analysis. I’m very numbers-oriented and I tend to read much into small samples early in the year. Being able to scout players is something I’m trying to work on. Thanks again, this was fantastic. Bookmarked.

    Like Mike P. up there, James Shields is the name that comes to mind after reading. I’ve noticed what Mike has, that the velocity is up but the swinging strike and contact %s are in line or even worse than his previous levels.

  4. Nutlaw said...

    Very interesting stuff. That made for a nice read.

    One question, however. In at least a couple of places, you make mention of strikeout rates being affected by stadium. I’ve never heard of that. Why would that be?

  5. Derek Carty said...

    Thanks, Mike.  I don’t see a whole lot to support Shield’s strikeout-per-inning.  His fastball is up about a MPH, which should add some strikeouts, but not as many as he’s getting.  It should be noted that his change is also coming in about 1 MPH faster, though.  He is, however, getting a lot more swings-and-misses on the change this year.  The only real difference I see in it is the 1 MPH speed increase and that it appears to be getting about an inch more arm-side run.  It looks like he’s throwing more 2-seamers than 4-seamers, although it looks like his fastballs are being classified differently this year, so I don’t think that says much.  And 4-seamers generally are better for strikeouts anyway.  His other pitches seem to be moving about the same.  If anything, his slider/cutter seems to be getting a little less tilt, although that could be the sample size talking.

    I’m only taking a cursory look here, but I don’t see anything that jumps out.

  6. Derek Carty said...

    I know Chavez has an ERA over 7, but a lot of that is bad luck (brought on by the small sample size).  His xFIP is 4.43 (and that would be much better if he were getting league average GBs like he did in 2008/2009).  Also, I’m mostly focusing on the K/9 here, using this exercise to see if this kind of analysis can predict players sustaining their K/9 rates (not to suggest that this will be in any way conclusive at the end of the year anyway, but it’ll be fun to look at).

  7. Derek Carty said...

    This is a question I get often, and people often don’t realize that parks can affect strikeout rates – and quite dramatically, at that.  The first person I know to talk about this was THT’s David Gassko a couple years ago here: http://www.hardballtimes.com/main/article/batted-balls-and-park-effects/

    While I don’t think we have a definitive answer for the “why” (David suggests that “humidity is one of the biggest determinants of strikeout park effects”), the effects are absolutely observable, and the numbers I present use 4-years of data (2006-2009) and are properly regressed to the mean, so they should be pretty reliable.

    Parks also affect things like walk rate, ground ball rate, pop-ups, and basically everything else that happens on a baseball field – just not always to the extent of HRs or Ks (or to any significant extent at all).

  8. Brian Cartwright said...

    Oliver uses a K park factor of 0.91 for PNC Park and 1.03 for Turner Field.

    At higher elevations it’s harder to get a pitch to break resulting in higher contact rates – fewer SO and also fewer BB as there are not as many deep counts.

    There are other stadium specific things such as hitting background, but they are hard to identify.

  9. Derek Carty said...

    Thanks for chiming in Brian.  For the record, I’m using K park factors of 0.924 and 1.041, respectively, so we’re close.

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