from Amazon
Thursday, July 31, 2008
ABSO-lutely… not!
Doomed to repeat history are these three posts. I want to highlight these posts because while it tries to make a good effort to make a good estimate, the author doesn’t provide the proper framework to test his work. It must be done against realistic averages, and not simply looking at that someone goes 1 for 4 or some sh!t like that. I provided the proper framework last year. I’m going to make an authoritative statement so that it leaves no doubt where I stand: you must use the plus 1 method (or differentials). Anything else that anyone does is almost certainly mathematical gymnastics that gives sabermetrics a black eye and proves that there are damned lies and statistics.
Anyway, using the plus 1 method, here are the corresponding LWTS values, if we force the out value as minus .28 runs, for 3 different metrics:
event OPS 1.75*OBP+SLG (BA+OBP+SLG)/3
1b 0.45 0.48 0.53
2b 0.83 0.77 0.81
3b 1.22 1.06 1.09
hr 1.60 1.36 1.38
bb 0.23 0.31 0.17
out (0.28) (0.28) (0.28)
The first result is OPS
The second result is 1.75*OBP+SLG
The third result is (BA+OBP+SLG)/3
For those of you familiar with Linear Weights, you know that 1.75*OBP+SLG gives a pretty darn good result here. And “BA+OBP+SLG” is ok for everything, except the walk. The walk is enormously undervalued here. While it reigns in the HR value properly, it does so at the expense of the walk.
I understand the author wants to sell the public something. But if you are selling the public cr@p, that’s not a good thing, even if it’s an easy sell. You can try whatever combination of OBP, SLG and BA you like, and you will invariably end up to something very close to 1.75*OBP+1*SLG+0*BA.
That’s the reality to deal with.
***
Die OPS+, die. It’s lipstick on a pig. OPS+ is, under the covers, something like 1.25*OBP+SLG. Here is what those Linear Weights give you:
event 1.25*OBP+SLG
1b 0.46
2b 0.81
3b 1.16
hr 1.50
bb 0.26
out (0.28)
The gap between 2b and 1b should be .30 runs, not .35. The gap between the 3b and 1b should be .58 runs, not .70 runs. And the HR value should be 1.40 runs, not 1.50. The BB walk should be .16 runs less than the 1B, not .20 runs.
As you can see, OPS+ is biased toward power hitters, notably HR, and biased against guys who walk. Any study that uses OPS+ and doesn’t account for this bias is flawed if it is trying to distinguish between power and walks.