Saturday, February 2, 2008

How Well Has Roger Clemens Aged?

You might wonder if a guy who is able to maintain or improve his performance as he aged had a little help from steroids or some other chemical enhancer. You probabaly heard about Roger Clemens' agent writing a report to refute claims that he took steroids. JC Bradbury took a look at this and you can read what he had to say with What Do the Statistics Say about Roger Clemens’s Steroid Use?. The report by Clemens' agent can be read by clicking here. What I do here is to see how Clemens did from age 40-44 compared to how he did from 35-39 and then compare that to the performance changes of other pitchers over the same ages. All the data comes from the Lee Sinins Sabermetric Encyclopedia. I found the 53 pitchers who had at least 500 IP from 35-39 and 200+ IP from 40-44. In general, Clemens does much better at the older age. But he is not always first or close to first in the rankings of the various stats. (click here for part 2 of this study.)

I also wrote a couple of articles called "Did Roger Clemens Have the Best Age-Adjusted Season Ever in 2005?" (parts 1 and 2) a couple of years ago. You can read them here and here.

First, let's see who the best pitchers were past the age of 39. The following table shows the top 15 pitchers with 200+ IP. The 161 for Wilhelm means that he was 61% better than the average pitcher in ERA. Clemens is near the top. Wilhelm was a knuckleballer. Smoltz does not have that many IP. Lyons and Hevving were old during WW II. So Clemens really stands out.

The next table shows the increase or decrease in ERA relative to the league average going from the ages 35-39 to 40-44. Rogers had a 99 from 35-39, meaning he was 1% worse than average. He had a 119 when he was 40-44, meaning he was 19% better than average. Then 119/99 = 1.20. So taking the league average into account, Rogers was 20% better at the older age. Of course, Clemens is up there and has alot more IP than Rogers or Seaver.

The next table shows how much they increased or decreased in SO/BB ratio. Ryan has 30% at the older age. His SO/BB ratio was 2.25 at the younger age while the league average was 1.72. 2.25/1.72 = 1.30. So he was 30% better than average in the younger years. But he was 70% better than average during the older years. His SO/BB ratio was 2.95 while the league average was 1.74 (2.95/1.74 = 1.70). 1.70/1.30 = 1.30. That is why Ryan is 1st below at 1.30. Clemens does make the top 15. He was 5% better.

The next table shows the change in allowing HRs. In the younger years, Seaver gave up 93 HRs while an average pitcher would have given up 72. So Seaver gave up 29% more HRs (93/72 = 1.29). In the older years he gave up 39 while the average was 46. He gave up 15% fewer HRs than average (39/46 = .85). Since .85/1.29 = .66, Seaver's rate of giving up HRs at the older rate was just 66% that of his younger rate. Clemens also made the top 15 here.

The next table shows how many runs per 9 IP each pitcher gave up in the older years relative to his younger years. For this, I used a stat from the Lee Sinins Sabermetric Encyclopedia called RSAA which shows how many fewer runs a guy allowed than the average pitcher while adjusting for park effects. I first adjusted each guy to a league with 4 runs per 9 IP. Clemens has 3.10 runs per 9 IP at the younger age and 2.63 at the older age. Since 2.63/3.10 = .85, Clemens only gave up 85% as many runs at the older age than he did at the younger age.

The next table simply shows how the best pitchers in terms of how many more or fewer runs they saved at the older age compared to the younger age. Ryan gave up 21 fewer runs than average (park adjusted) at the younger age but 69 fewer at the older age. So he improved by 48. Very few guys saved more runs at the older age. Clemens does well here, too.

The last table just shows the leaders in terms of change in IP. Ryan was actually the only one to pitch more innings. There may be others who did, but they don't meet the qualifications I set out at the beginning.

(click here for part 2 of this study.)


Minus said...

The problem with this analysis is your just lumping in a group of seasons together. Clemens steroid use seemed to be happening in certain seasons, during certain periods of time. Your probably better off looking at every single season of clemens post boston career, and trying to figure out if clemens has any weird or strange jumps that coincide with the times mcnamee allegedly injected him.

Cyril Morong said...

Thanks for droppng by and commenting. You are right that individual seasons should be looked at. I do have links to articles I wrote specifically about his 2005 season. I think JC Bradbury does a good job of doing what you suggest.

Minus said...

I decided to take a look at clemens ERA during the "before and after" periods of when McNamee allegedly injected him, and all three years show a decrease in ERA. This may very well mean nothing, but his 1998 season sticks out to me as the most interesting. Before Mcnamee in 98, clemens boasted a 3.27 ERA, and was averaging 9.18 K/9. Then comes McNamee into the picture, and Clemens posts a 2.29 ERA in more innings pitched, and averages 11.11 k/9. He ends the year setting his career high in that stat. The biggest question in my mind was: What does this all mean? do steroids enhance peformance that fast? was it all just a placebo? What about his 97 season? Was he juicing then too? what about in 1999? it's really very hard to say whether or not steroids effected his performance. in some years it look like it did, and some others it just doesnt seem so. Hopefully we'll learn more about the extent of his use in the future, if he even used them in the first place.

Cyril Morong said...

I don't know how fast steroids work if they work at all. Those are questions that should be answered but I don't know how to do it.

In 1998, Clemens had 10.39 strikeouts per 9 IP. That was his career high, but less than the 11.11 you show. Where is the 3.27 ERA before 1998 coming from? His career ERA before then was 2.97. His ERA in 1997 as 2.05.

You are referring to swings in his ERA. He has had them other times in his career. It fell from 3.13 in 1989 to 1.93 in 1990. Here are his ERAs from 1992-1996


We could say he juiced in the good years and not in the bad years. But then we are claiming he has been juicing on and off for most of his career. The question is are his swings unusual? Are his swings so much different than what other pitchers ever had that they bear closer scrutiny?

Minus said...

"His career ERA before then was 2.97. His ERA in 1997 as 2.05."

I was talking about his ERA in 98 prior to mcnamee, and the same goes for his k/ip. I wasn't talking about his career ERA. I never mentioned anything about his previous career numbers. I'm just going by what's in the mitchell report. When Mcnamee supposedly started to inject clemens, his ERA did in fact decrease during 98, while he started striking out more batters per 9 innings. This could very well mean nothing, or it could mean steroids had a very positive effect on his performance.

Phil Birnbaum said...

Here's a question I haven't seen answered yet: what kind of improvement could a pitcher expect from going on steroids? It seems like nobody knows the answer, but it doesn't stop anyone from looking for evidence in the statistics ...

If it's a small amount -- say, 0.25 in ERA -- it would take a pretty big sample to notice it.

Cyril Morong said...


Thanks for the clarification. Pitchers can have good first halves and bad second halves and vice-versa. The thing to would be to see if any swing that Clemens ever had is alot bigger than what anyone else ever had.


Thanks for dropping by. I think you raise a very important question. I don't think anyone knows how much steroids add. Maybe it would take controlled experiments, which I don't think will ever happen. But I think to even say "maybe a guy used PEDs," I want to see some unusual statistical pattern (absense any kind of blood/urine test). I don't even know what kind of testing program is appropriate.

Minus said...

". But I think to even say "maybe a guy used PEDs," I want to see some unusual statistical pattern (absense any kind of blood/urine test). I don't even know what kind of testing program is appropriate."

Not everyone is barry bonds. A lot players have been using earlier in their careers, so numbers may not indicate something suspicious since the use of the drugs has been going on for a very long time.