Baseball Musings: Regression to the Mean

October 23, 2006

Regression to the Mean

Double Play Depth believes that Kenny Rogers post season is simply the law of averages at work:

My theory on Kenny Rogers goes like this:
Law of Averages.

Sure, he was Awful before, and he's been Great this year, but the average of Awful and Great is Mediocre, which is exactly what Kenny Rogers has been over the course of his career. When you add up his career postseason numbers, they look like this:
             IP    H   ER  BB   SO   W   L  ERA
New Kenny   23.0    9   0   7   19   3   0  0.00
Old Kenny   21.1   37  20  16   15   0   3  8.44
All Kenny   44.1   46  20  23   34   3   3  4.06

The law of averages is not like the law of gravity, however. The law of averages is just a good idea.

The thing that is suspicious to me is his strikeout numbers. Kenny hasn't posted a decent strikeout rate since 1999. Over the last seven seasons, his strikeout rate is 4.9 per 9 innings. This post season, it's 7.4 per 9. Plausible? Sure, especially since he did the same thing earlier this year.

People should be suspicious of a substance on a pitcher's hand. But we should be open to other explanations as well.

Update: Since two people mentioned this, I'm not implying steroid use in the last sentence. I'm implying non-cheating explanations, such as luck!

Strikeouts have more to do with fooling batters than overpowering them. A big increase in strikeouts might mean the ball is moving more for Rogers, and a substance on the ball might do that. That's why I find the strikeouts suspicious. But as I point out, he's had a good three game run of strikeouts this season, so while it's unusual, it's not out of the realm of possibility.

Posted by David Pinto at 04:26 PM | Post Season | TrackBack (0)

Comments

I guess we now have proof that you can, indeed, use statistics to prove anything.

Posted by: SleepyCA at October 23, 2006 06:59 PM

ya it seems that kenny did use pine tar is pretty obvious

Posted by: Hotcorner at October 23, 2006 08:47 PM

re: kenny rogers success

i'm sure when a pitcher has three shutout games in a row you could say it's the law of averages.

or you could say he's doing things and going places that only schilling or hershiser or johnshon or gibson or lolich have gone before.

no matter how you cut it, rogers is turning out at age 41 to have the big game clout of a jack morris or a curt schilling or any other HOF big game pitcher.

Game 2 was a must win do or die for the Tigers, and Rogers pitched like it mattered and like he cared, not like he was an overpaid pro.

--art kyriazis, philly

Posted by: art kyriazis at October 23, 2006 09:06 PM

David, do I correctly take your final sentence ("But we should be open to other explanations as well") as well as your characterization of Rogers' increased K per 9 as being "suspicious" to be a suggestion that Rogers might be using steroids? Because I've heard those suspicions aired before. On the face of it there's no reason why it's impossible, but of course there's no proof in any way (or even "smoke" that would indicate a "fire," so to speak).

Perhaps I'm reading too much into this. Perhaps not. I know you take a much less hardline stance on the use of PEDs in the game than many other sportswriters, so I don't really think you're intending to cast aspersions upon Rogers if indeed that is what you're suggesting. But since I value your opinion so much, I would be interested if that is indeed what you were implying.

Posted by: Jeff B. at October 23, 2006 10:12 PM

And indeed, yea verily, I use the word "indeed" too much in my writing. Twice in a sentence = inexcusable sin.

Posted by: Jeff B. at October 23, 2006 10:13 PM

Jack Morris or Curt Schilling or any other HOF pitcher? Rogers is like any other HOF pitcher? Since when does 1 season get you into the Hall? The guy has taken over $66 million of fans' money over many years and done little more than break their hearts.
He faced Denny Neagle 10 years ago today in game 4 of the World Series and gave the team only 2 IP and gave up 5 runs. One thing about him is sure--he's very lucky to be where he is today. Save the adoration for pitchers who've done it for their team consistently every year for
over 10 years, not Rogers.

Posted by: susan mullen at October 24, 2006 01:44 AM

Whoa, whoa, whoa. Surely you know the Law of Averages doesn't work that way, David. If pitcher A is "naturally" a 4.00 ERA pitcher, and he goes one postseason at an 8.00 clip, regression to the mean simply means that we should expect him to pitch in the future like his normal self, not some super-powered version of himself to make up for the previous poor performances.

Posted by: Adam Villani at October 24, 2006 03:57 AM

Jeff B,

No, I meant that we should be open to non-cheating explanations, such as he's just on a hot streak.

Posted by: David Pinto at October 24, 2006 07:11 AM

Dave, I don't understand how you can find his 7.4 K's per 9 innings to be suspicious. You're talking about 23 innings of baseball. That's a fairly small sample size. A baseball player can do amazing things in just a few games of baseball. Hell, look at Chris Shelton's numbers after the first six games of the year.

.583 / .615 / 1.458

He finished the year playing in Toledo, and was left off of the playoff roster. Sustaining it is the hard part, and there's no reason to believe Kenny Rogers will go through next season sporting 7.4 K/9 because he did in just 3 incredible postseason outings.

Reading your last sentence, it seemed to me that you were implying potential steriod use. I really hope that's not the case. That's quite a leap, pine-tar to steroids?

Posted by: Bryan at October 24, 2006 07:47 AM

And I now retract my comment after reading your recent response. *doh*

Posted by: Bryan at October 24, 2006 07:48 AM

well

i have been hearing that his fastball is faster. pine tar will NOT do that. i can think of only one substance that can, if we get down to it..

and susan complaining about kenny's terrible performance for NY and talking about being consistent for 10 years - well NO pitcher has been lights out in the playoffs for 10 years. that is a really stupid complaint

Posted by: lisa gray at October 24, 2006 02:34 PM