Rotisserie Values and Pitcher Metrics: Part II

Last month, I examined the theory that certain pitcher metrics might be worthwhile in determining pitcher value. I concluded that K/9 is an excellent metric to determine pitcher value in Rotisserie, BB/9 isn't quite as good, and G/F is hardly a predictive metric.

Rotoman wanted to know if I could make one little substitution.

Not that you guys aren't busy, but it seems worthwhile at this point to run the same numbers substituting HR rate for G/FB.

I did this and added it to the spreadsheet I already created for this project. Table 1 below contains the previous results using G/F and the new results using HR/9.

Table 1

#	$ G/F	$ HR/IP
1-10	$407.36	$430.27
11-20	$258.43	$314.30
21-30	$178.70	$191.96
31-40	$151.44	$205.60
41-50	$96.98	$103.28
51-60	$101.83	$134.61
61-70	$163.23	$113.14
71-80	$128.80	$41.58
81-90	$79.54	$49.66
91-100	-$15.94	-$34.03

Rotoman's educated guess was quite correct. Substituting HR/9 for G/F makes these combined metrics far more predictive.

Table 2 breaks down each metric separately.

Table 2

#	K/9	BB/9	HR/9
1-10	$260.41	$242.49	$352.06
11-20	$296.38	$209.05	$236.87
21-30	$287.90	$185.55	$121.91
31-40	$207.02	$262.65	$207.24
41-50	$184.63	$158.24	$147.17
51-60	$140.65	$74.91	$157.50
61-70	$65.74	$79.96	$125.52
71-80	$50.80	$138.24	$92.77
81-90	$43.05	$77.29	$64.33
91-100	$30.79	$122.19	$45.00

HR/9 does nearly as well as K/9. The pitchers in the 21-30 grouping are significant enough of an outlier that K/9 still stands as a superior metric to use to tie performance to Roto value. However, it's close, and the best HR/9 pitchers simply blow away the best K/9 pitchers in terms of matching performance to value.

This is all very interesting to look at. However, all this really does is tell me a lot about last year's performance; it is hardly instructive in terms of analyzing future performance. Thanks to xFIP, we know that last year's low HR/FB pitchers are likely to regress to the median the following year.... if not sooner.

I can't read Eno Saris' mind, but this is what I believe he was trying to get to in his original piece that sparked all of this in the first place.

We do know that there are three main components to a pitcher's performance: How often do they strike a guy out, how often do they walk a guy, and how often do they get a guy to ground out. These three aspects of pitching are the parts of the game that a pitcher has the most control over. Generally, you want a pitcher to be above average or better in two of the three categories before you place your trust in them.

While HR/9 are predictive of Rotisserie value, they aren't necessarily predictive of how good a pitcher is, since home runs aren't as much in the realm of a pitcher's control as we used to believe they were. A pitcher with a high ground ball will allow fewer fly balls and in theory should allow fewer HR.

In practice, though, G/F by itself is nearly worthless, and definitely isn't as important as K/9 or BB/9. You want to get a guy who controls his own game by striking hitters out and keeping them off base by walking as few as possible, in that order. A strikeout pitcher who also generates a lot of ground outs is better than a strikeout pitcher who doesn't, but if you ignore G/F rates entirely, you'll still do pretty well if you only use K/9 when looking for arms for your staff.