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Wednesday, October 28, 2009
Is Ryan Howard really that bad versus LHP?
Many people, including some analysts, have suggested that Howard should be platooned. And that the Phillies might be in trouble in the WS because the Yankees are going to throw 4 or 5 lefties in 7 games. I think that the conventional wisdom is simply that Howard is not a good hitter versus a LHP.
I am here to challenge that wisdom of course. But, many of you will say, look at his stats versus LHP. An OPS of .719 in 890 PA over the last 4 years! Not too good. Not good at all.
I say, stats, schmats!
Try this one on for size:
Say we have two players. Both are left-handed. Player A has an actual wOBA versus RHP of .450. Against LHP it is .300. Again, those are actual numbers in say 3 full seasons.
Say player B is .350 versus RHP and also .300 versus LHP in the same number of PA (versus both RH and LH pitchers) in 3 seasons as well.
Who has the higher projection versus LHP and by around how much?
The answer is that Player A has a much higher projection versus LHP than player B, even though they both had the exact same historical performance in the same number of PA versus LHP.
How can that be?
Because how a batter does overall (versus lefties and righties) tells us more than just how he does against LH or RH pitchers alone, even if we want to estimate how they will do in the future against either lefties or righties alone.
IOW, how a batter does against RH pitchers informs us on how he will likely do against LH pitchers and vice versa. Why? Because there is not much of a spread in true platoon splits among ML baseball players yet there is a large spread in overall true hitting talent among ML baseball players. So if we see a large platoon split, like for a player like Howard, it is likely a fluke. If a player does really well versus RH pitchers but terrible against LH pitchers, both the “really well” and the “terrible” numbers are likely fluky and the “truth” is somewhere in between.
Howard has a .719 OPS in the last 4 years versus LHP. How would we estimate his “true” OPS versus LHP? You might be tempted to just use the .719, which is not too good or you might be tempted to use the .719 and then regress that toward the league average for a LH batter of Howard’s physical characteristics, which might be around the same or a little higher – I don’t know. Both of these methods would be wrong. You cannot ignore the fact that he also hit 1.052 in OPS versus RHP over the same time period (last 4 years) and in many more PA. This suggests that he is a very good hitter overall (which he is) and that the .719 is somewhat of a fluke.
Anyway, what would be the correct method for estimating Howard’s true OPS versus LH pitchers using his last 4 years of stats?
First we’ll estimate his overall true OPS. In his career, it is .966. We’ll regress that and call it .930, which is a typical projection for him. Now we have to take his observed platoon ratio (I like to use ratio – some people use a differential) and regress that. His observed platoon ratio for those 4 years is 1.052/.719, or 1.46. For the average lefty, it is 1.20 and we just don’t see that much variation among players in their true platoon splits. IOW, that 1.46 is likely very (but not completely) flukey. We might regress that 1.46 80% toward the league average of 1.20, to get 1.25. That is Howard’s “true” estimated platoon split.
Now we simply apply that to his overall estimated true OPS of .930 and the fact that he faced 62% RHP. That gives us an OPS of .805 versus LHP and 1.006 versus RHP.
.805 is a far cry from .719
So if we are going to talk about how Howard is likely to do versus LHP, let’s at least get our numbers right. .805 is higher than Werth and Jeter versus RHP. We don’t hear anyone talking about how terrible Jeter and Werth are versus RHP, which they face most of the time, do we?