Should the Indians trade Kelly Shoppach?
January 5, 2009 2 Comments
A few weekends ago, I was enjoying a leisurely dinner with a friend of mine from high school. He hit on the waitress, like he usually does, and we spent a good three hours talking about old times (including that one time when our friend Steve… oh nevermind), work, and of course, the Indians.
A brief transcript, that might have been slightly altered from the original, but not by much.
Friend: Pizza, you’re the world’s foremost expert on baseball, not to mention incredibly smart, debonaire, and otherwise better than me. What do you think will happen this off-season with the Indians?
Pizza Cutter: Not really sure yet.
Friend: Oh, come on, you are the smartest guy I know, and your knowledge of baseball is un-matched. Surely, there’s something brewing.
Pizza Cutter: It’s really hard to tell. They might, they might not.
Friend: Do you think that the Indians will trade Kelly Shoppach?
Pizza Cutter: Funny that you mentioned Shoppach. I just happened to be doing some research that is pertinent to this very issue. In fact…
Shoppach is one of the more interesting names on the hot stove this winter. He’s a catcher, and everyone needs one of those, lest (as Casey Stengel reminded us) you have too many passed balls. But Shoppach, in addition to strapping on the tools of ignorance, is also good at something else. He’s one of the most purely powerful hitters in baseball. In fact, when I ran my power scores for the 2008 season, Shoppach rated as the 11th most powerful hitter in baseball (min 100 PA). Well, that is when he actually hits the ball. When I ran my plate discipline numbers for Shoppach in 2008, he came in near the bottom of that list.
Shoppach got his big chance in 2008 when Victor Martinez went down with an injury early in the year and didn’t re-appear until late August. In 403 PAs, Shoppach hit 21 HR, to go with 27 doubles, and… 133 strikeouts. He’ll be 29 next year, and with Martinez back and healthy, Shoppach is a backup that would probably make some team looking for an upgrade behind the plate rather happy. Throw in the fact that the Indians still have a few needs here and there, so perhaps a trade could be worked out. Then again, maybe they shouldn’t. V-Mart is an injury risk and there’s been talk of a permanent move to first base, and so it would be nice to have a guy like Shoppach around just in case. You can never have enough pitching. Or catching.
But oh my, what to do about those strikeouts! Shoppach does hit about 20% of his fly balls out of the yard (nice!), but is that worth a strikeout rate over one third? It’s the curse of a power hitter to strike out a lot… but then again young players do learn things. Maybe since he’s only 29 this coming year, things might get better? If Shoppach could cut back on his strikeout rate by even five percent, the Indians would have a monster hitter on their hands. And at that point no matter what they get back, in hindsight, trading Shoppach would probably look about as silly for the Indians as a team trading away Brandon Phillips… oh right…
Does plate discipline really improve with age? We know that as players age, they walk more, but that has less to do with their plate discipline skills than the fact that they simply swing less often. Still, there might be something to be learned as players grow up. They’ve seen more pitchers and pitches over the years. Maybe, just maybe, there’s hope for Kelly Shoppach.
I took this opportunity to break out a new statistical tool called mixed linear modeling. It’s not really new since it’s actually the process that gives me intra-class correlation, which I reference quite a bit, but MLM is a more fully developed case of intra-class correlation. It’s regression-based, but allows for the use of repeated measures, as well as covariates. It also allows for fixed and random effects to be used (and if I wanted to, hierarchical terms). If you don’t understand that last sentence, just nod and say, “Ooooh, pretty!”
What intra-class correlation tells you is how much of the variance is accounted for by factors within the player himself. What we’re going to try to do is to “steal” some of that variance by adding additional variables and wrinkles into the model to see if some of that variance will wash out. If what was once explained by ICC can be explained by controlling for other factors, then perhaps players aren’t simply doomed to repeat their past performances. We simply need to install other skills in them. Easy enough, yes?
I took all player-seasons from 1993-2008 and calculated the player’s age and his sensitivity rating using my plate discipline measure. I restricted the sample to those who had more than 100 PA, which had the nice side effect of getting rid of (most of) the pitchers batting. (Somehow, Randy Johnson logged 104 PA for the Diamondbacks in 1999. He was easy to spot… it was the worst season for plate discipline in the whole sample.) I looked at the ICC for sensitivity over a player’s whole career (with age as the repeated measure) and it came out to .75, which is really really high. That means that a player will be very consistent from year to year of his life in terms of his plate discipline.
However, the good news for Shoppach is that what small trend line for change that there is does point upward. (I ran a simple linear regression looking at age predicting sensitivity.) The bad news is that it points upward ever so slightly, to the point where it’s a negligible effect. A player would have to play for 20 years to get anything remotely resembling a decent effect out of it.
But then we have a very wide and heterogeneous sample in looking at all major leaguers. We need to cut down the sample to those who are more like Kelly Shoppach. Shoppach debuted in the majors when he was 26 years old. This is important. The players who get “the call” at 23 are a different set than those who get “the call” at 26 or 28 or 30. Shoppach has also survived to play until age 29, meaning that he was not a “cup of coffee” guy. I looked for guys who debuted at 26, and were still playing at age 32, which seems a pretty safe bet for a guy like Shoppach. In that sample, the ICC budged downward to .73. Oh dear, no luck there.
Well, let’s try some other tricks. Let’s add some covariates to the model to see if that helps. In MLM, there are two types of effects: fixed and random. (Warning: technical lecture follows) A fixed effect is much like the regression equations that you are used to. Everyone’s data points get thrown into a big hat and the program tries to find a line that shoots roughly through the middle. A random effect, on the other hand, treats each person as if they are their own regression line over time, with its own slope. Clearly, it won’t be able to tell me what the slope of the overall line is, but it will be able to tell me whether those slopes are consistent or inconsistent, and how much of the overall variance in each case is accounted for by the variability in the slopes.
I added in pitches per PA in as a covariate, first as a fixed effect. I added in swing percentage. Neither got me below .70. Then, I tried contact percentage. That dropped the ICC down to .64, which is a small, but significant effect. This says that plate discipline is, in some small part, the ability to make contact, which of course, surprises no one. The problem, of course, is that contact percentage is pretty stable over time too, and we haven’t explained all of plate discipline by a long shot. I took all three (PPA, swing%, contact%), and put them into the same regression, plus all possible interaction terms. The ICC was still at .60. Even allowing the covariate effects to be random, the lowest I could get the intra-class correlation was down to .52. Even controlling for all of these factors, the intra-class correlation, which is a measure of how much of the variance in the dependent variable (plate discipline) is related to factors specific to the individual, just won’t go away.
Originally, plate discipline had an ICC of .73, which has an R-squared value of 53%. After controlling for all the factors I mentioned, it dropped to 27%. So, half of the repeatable variance can be accounted for by controlling for those other variables, although these variables have also been shown to be remarkably stable. Batters who see more pitches per PA, swing less, and make more contact have better plate discipline ratings. Considering that my plate discipline measure is a strike-avoidance measure, that’s probably not a surprise. So, perhaps the Indians might counsel Shoppach to be a bit more patient and not swing as much and practice hitting more often for contact.
There’s a problem. We know that swinging for contact and swinging for power seem to be two ends of the same spectrum. You can aim to hit for power, but will sacrifice contact. You can aim to hit for contact, but will sacrifice power. So, while the Shoppach might be able to learn to hit for contact (and no one’s done studies on how teachable these skills are), but he’d probably lose some of that pure power.
Then there’s the issue of extending his at-bats out more. This can be done by fouling more two strike pitches off or taking more pitches in the hope that some of them are balls. The former is a contact skill, which is good to have, but again, we don’t yet know if it can be taught. The latter wouldn’t be wise in Shoppach’s case. My plate discipline measure has a companion measure called response bias. It gives us a rough estimate on whether a player is more likely to push the “swing” button or the “take” button. The perfect number is 1.00. Higher than 1.00, and the player would actually have fewer strikes on him if he swung less. Lower than 1.00, and he’s not swinging enough. Shoppach in 2008, was actually a .988 (which is really good!), although it means that if anything, he needs to swing a tiny bit more, but he’s so close to 1.00, that I wouldn’t tinker with that aspect of his game.
The moral of the story appears to be this. Yes, players do get ever-so-slightly more disciplined as they age, but the ones that have the A-ha! moment are few and far between. Plate discipline and the skills that go with it are pretty well-wired into a player, at least by the time he makes it to a major league roster. Kelly Shoppach probably won’t learn to strike out less, or at least he’s not a really good bet to do so, not without sacrificing some power in the process. He’ll probably always be a guy who’s a member of the Russell Branyan school of “swing real hard in case you hit it.” Now, given what Shoppach did last year, in terms of results, that’s not a bad player. As frustrating as the strikeouts were, the value that he added with all the doubles and home runs was also worth a lot to the Indians. (There’s a difference between a player being frustrating and a player being valuable. The game is about winning, not pleasing the eyes.)
Should the Indians trade him? Well, a trade should always be evaluated based on what you get back (Shoppach for Pujols and Lincecum? Deal!), but the Indians probably wouldn’t be trading away a player about to emerge from being a grubby caterpillar to a beauiful butterfly if they decided to part ways with Shoppach. He’s probably going to continue to do what he’s been doing and should be valued accordingly. And a catcher who has a bit of pop, even if inconsistent, ain’t a bad commodity to hold or to trade.