MLB Forum

Predicting pitcher performance

Posted By: Colin Caster
Date: 1 Aug 01, 11:54 pm

In Response To: We tried to warn you. :) (nt) (StevieY)

I considered leaving the text of this message blank. From season to season, pitching performance is so highly variable, and there don't seem to be many trend indicators (e.g., age for batters). Harv was trying to use K/BB ratios to predict a decline in Hermanson's performance (or to detect an injury). Here are some of the data Harv saw:

Season  K/IP   K/BB

1998    0.82   2.75

1999    0.67   2.10

2000    0.47   1.25

Pretty dramatic, I have to admit. Looks like he's falling apart. But I think that unless there is really compelling evidence corroborating an injury (i.e., physical, not post hoc explanations of poor performance by talking heads) we ought to be skeptical of temporal trends in pitching performance, using instead recent averages or career averages as best predictor of future performance.

Here's Hermanson so far this season:

Season  K/IP   K/BB

1998    0.82   2.75

1999    0.67   2.10

2000    0.47   1.25

2001    0.68   1.80

1998 appears to have been "lucky" and 2000 appears to have been "unlucky," relative to current performance, thereby leading to the impression that he was in decline. Take a look at these numbers:

Season  K/IP   K/BB

98-00   0.65   1.97

career  0.69   1.89

2001    0.68   1.80

Looks like, in this case, mass aggregated data nailed 2001 (so far) very well. Obviously, one shouldn't expect this kind of accuracy with regularity, given the variability that has already been demonstrated.

Anyway, it looks good for my side of the Colin Caster/Harvard Chu Hermanson bet. Thanks to his super July, Hermanson will need to post about a 6.0 ERA from here on out to move his season ERA over 5.0. Barring an accident, he should not have difficulty meeting the innings requirement either. The Cards' schedule is even pretty favorable for Hermanson: no games at Coors, one three-game series at Enron (go Bud Smith!), and lots of cupcakes.

Sorry, HC, if this sounds like piling on. I know you've said that this has been a bad season for you, bet-wise. But (in case anyone hasn't noticed) I've had a miserable two weeks myself. I need a little self-indulgence!

Cheers,

CC

Messages In This Thread

How about that Dustin Hermanson? :-) (nt) -- Colin Caster -- 21 Jul 01, 10:24 pm

Grrrr (nt) -- Harv -- 1 Aug 01, 3:47 pm

We tried to warn you. :) (nt) -- StevieY -- 1 Aug 01, 5:33 pm

Predicting pitcher performance -- Colin Caster -- 1 Aug 01, 11:54 pm

From what I have seen... -- StevieY -- 2 Aug 01, 6:03 am

StevieY is right -- Harv -- 2 Aug 01, 4:10 pm

Agree that July has made the difference -- Colin Caster -- 3 Aug 01, 12:06 am

Hermanson -- StevieY -- 3 Aug 01, 11:23 am

I mean Sunday (nt) -- StevieY -- 3 Aug 01, 11:28 am

Hermanson on Sunday -- Colin Caster -- 6 Aug 01, 2:16 pm

Hermanson -- StevieY -- 6 Aug 01, 2:35 pm

LOL -- Colin Caster -- 6 Aug 01, 3:54 pm

Stevie, you mentioned.. -- Roz -- 6 Aug 01, 2:45 pm

Answer -- StevieY -- 6 Aug 01, 2:57 pm

Strike three==Yurrr Out! -- Jimbo -- 20 Aug 01, 9:02 pm

Difference -- StevieY -- 21 Aug 01, 2:11 pm

Ryan -- Jimbo -- 21 Aug 01, 3:44 pm

Yeah but, -- StevieY -- 21 Aug 01, 4:24 pm

Again -- Jimbo -- 22 Aug 01, 1:55 am

Sinker/slider pitchers -- StevieY -- 22 Aug 01, 2:33 pm

MLB Forum is maintained by Pi Yee Press