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April 16, 2009

Checking the Numbers

Keeping Rare Company

by Eric Seidman

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While revisiting the 2008 dominance of Cliff Lee last week, we investigated how pitchers with similarly large spikes in ground-ball rates have fared in subsequent seasons. The results weren't pretty, and showed that massive rate increases in this area have been few and far between since 1954, and a very low percentage of these pitchers have been able to sustain these higher rates. The research in no way invalidated Lee's success, but rather suggested that factors outside of a change in approach could have an influence on his 2009 performance. Hurlers intent on inducing grounders tend to follow a different set of rules when it comes to HR/FB rates and their percentage of unearned runs than do their fly-balling colleagues, and the group relies on defense more than those whose skill is missing bats. Combine all of these ingredients, and it becomes evident that even if Lee were to become just the fourth post-1994 pitcher to increase his ground-ball rate by at least eight percent and then see it fall no lower than three percent over the following three seasons-all while meeting respectable playing time qualifiers-he is still not guaranteed even a fraction of the success he experienced last season.

Lee's ground-ball rate had a performance-altering accomplice last season in his unintentional walk rate. Following a 3.24 UBB/9 in 2007, Lee pared his free passes to a Maddux-esque 1.33. Calculating the UBB/9 in my database involved the prerequisite coding of innings pitched, and in order to keep everything consistent for the purposes of this article, I re-ran the ground-ball rate queries with total innings as opposed to the batters-faced numbers used last week. Since Lee threw just over 97 innings in 2007, the minimum was set at 95, requiring a pitcher to have thrown at least that many innings in the year of the rate increase and the year prior in order to be included.

From 1954-2007 there have been 1,123 unique pitchers who threw 95-plus innings in consecutive seasons on at least one occasion. This group actually produced 5,031 such instances, since many of the pitchers satisfied the innings criteria on multiple occasions. Looking for ground-ball rate increases of at least 8 percent from one season to the next among all of these cases returned 254 unique pitchers and 288 total occurrences (some accomplished this more than once). These rate spikes have occurred in just 5.7 percent of the 5,031 total instances during this span of over 50 years.

Moving forward one year, 99 pitchers (in 106 pitcher seasons) of the remaining 254 had rate spikes and were able to maintain them while meeting the innings-pitched benchmark. Finally, 59 (in 61 pitcher seasons) of the 99 pitchers capable of sustaining the rate in the year following the increase were once again able to record ground-ball frequencies in the same general vicinity. The rising percentages here can be a little misleading; few pitchers in the sample were able to establish the change as a new skill. Simply put, a pitcher has been able to boost his ground-ball rate as significantly as Lee had last season and then post equable rates over the following two seasons in just 1.2 percent of the situations in which they pitched over 95 innings in consecutive seasons.

How do unintentional walk rates fare in this regard? Lee cut his UBB/9 by almost two full walks last season, but since similar occurrences are incredibly rare, we'll adjust the minimum drop-off to one and a half free passes. The larger sample of 5,031 instances meeting the innings-pitched qualifier is still intact, and just 131 pitchers were able to cut their unintentional walk rate this much from one year to the next (143 instances). Of those 131, 60 were able to either shave their walks even further in the following season or regress by no more than 0.3 walks per nine innings (65 instances). Extending out one more season, 27 of the 60 who significantly reduced their walk rate and then held steady in the next season were again able to keep their UBB/9 in the same neighborhood as the first year (30 instances), so that less than one percent of the overall sample were able to reduce their walk rates as much as Lee had last season, and then repeat the new skill over the following two years.

Suffice to say, increasing a ground-ball rate or decreasing a walk rate to the extent of Lee's statistical shifts last season is very rare, and even rarer are the number of pitchers who were able to establish these new rates as legitimate skills. Lee, however, accomplished both of these changes in the same season. The data mentioned throughout this article are independent of one another, but what happens if the two rates are combined? Between 1954 and 2008, only 10 pitchers have reduced their walk rate and increased their ground-ball rate to such an extent in the same season, and two of them happened to accomplish the feat last year. In addition to Cliff Lee, there was another pitcher whose effort went largely unnoticed in '08: Carlos Villanueva of the Milwaukee Brewers.

Below is the complete list of the 10 pitchers and their rates. (Keep in mind that these ground-ball rates, courtesy of Retrosheet, are different than those offered by Baseball Info Solutions that can be found on other sites.)


Player             Years   GB1  GB2  UBB1  UBB2
Ray Lamb          1971-72  .49  .61  3.52  2.01
Mike Norris       1979-80  .48  .56  5.23  2.56
John Denny        1982-83  .66  .74  4.48  1.78
Al Leiter         1997-98  .40  .49  5.17  3.22
Dwight Gooden     1999-00  .35  .47  5.01  3.51
Steve Sparks      1999-00  .43  .52  5.00  2.51
Kevin Appier      2000-01  .43  .52  4.24  2.61
Daniel Cabrera    2006-07  .41  .49  6.26  4.49
Cliff Lee         2007-08  .36  .45  3.24  1.33
Carlos Villanueva 2007-08  .37  .48  3.94  2.41

Of the eight pitchers other than Lee and Villanueva, six logged 95 innings or more in the season following their remarkable rate changes. Only Daniel Cabrera and John Denny fell within the +0.30 maximum UBB/9 increase, and only Cabrera and Steve Sparks produced similar ground-ball rates. Cabrera is the only other qualifying pitcher we have on record who had these changes and sustained them in consecutive years, and as we discussed prior to the season, Cabrera now appears to be on the last legs of his career; he may struggle to hold down his rotation spot for the lowly Nationals in the coming months.

Many analysts, myself included, chalked up Cliff Lee's tremendous 2008 season to his change in approach, as he attacked hitters in order to limit free passes and pitch to contact. When his luck-based indicators normalized, it became clear that Lee's season was no fluke. What we failed to take into account was the rarity of such drastic changes in both unintentional walk and ground-ball rates. Lee, and Villanueva for that matter, may become precedent-setters if these rates can be sustained this season and beyond, but history is certainly not on their side. Granted, past performance does not always accurately project future results, but we have all underestimated the rarity of Lee's and Villanueva's accomplishments last season. Even if the new rates stay put, there are several other factors that could drag down their performance lines, but the historical odds are slim to none that they'll be able to avoid regression or fluctuation. To date, Lee's two starts and the three appearances by Villanueva constitute far too small of a sample from which to draw any conclusions, but it will be interesting to track their rates as the season progresses, and monitor their positions relative to last season as well as how they affect the overall results.

Eric Seidman is an author of Baseball Prospectus. 
Click here to see Eric's other articles. You can contact Eric by clicking here

Related Content:  Walk Rate,  Carlos Lee,  The Who,  Ground-ball Rate,  Cliff Lee

17 comments have been left for this article. (Click to hide comments)

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omarwhite

Although outside study parameters (because of low innings in 2007), Jon Lester saw very similar spikes in ERA, BB% and GB% (comparing his aggregate 2006-2007 numbers versus 2008 numbers).

Apr 16, 2009 10:04 AM
rating: 0
 
BP staff member Eric Seidman
BP staff

Yep, my DB has Lester going from 0.35 to 0.49 in GB Rate from 2007-08 and from 4.43 to 2.78 in UBB/9. However, his 2007 innings weren't high enough to qualify for the study. Despite that, he too might be someone to keep an eye on based on the extreme rarity of pitchers sustaining such shifts.

Apr 16, 2009 10:15 AM
 
leez34

Even so, this doesn't explain Lee's hammerings early in the season, does it?

Either way, fine work. You're certain to be hired by a front office soon...

Apr 16, 2009 11:37 AM
rating: 0
 
BP staff member Eric Seidman
BP staff

Nope, doesn't explain them and I didn't intend to try... it's just two starts. After four starts in 2008, Sabathia had 18 IP, 27 H, 32 ER, 16 BB, 16 K. He turned out just fine. This data in conjunction with last week's piece really shine light on two major things:

1) Groundball pitchers follow different rules so even if rates are sustained, several factors can worsen one of their performance lines in a given year.

2) Reducing a UBB/9 and increasing a GB_Rate as drastically as Lee did last year is incredibly rare and nobody other than Daniel Cabrera, since 1954, has been able to sustain both rates in the following season.

And thanks for the compliments!

Apr 16, 2009 11:57 AM
 
Aaron W

Just curious, but does basing his walk rate off his horrible 2007 season give us a good benchmark? As I recall, Lee was relatively stingy with walks prior to that year anyway. Are the changes as significant if his career rates are considered?

Apr 16, 2009 16:44 PM
rating: 0
 
BP staff member Eric Seidman
BP staff

Well you're combining different things there... the point here was to investigate how pitchers with rate changes have historically fared... it's essentially independent of Lee. The idea was derived from Lee's shift from 2007 to 2008 but the goal here wasn't necessarily to investigate Lee as much as other pitchers with similar rate changes... just centered around someone who famously experienced such shifts last season.

Apr 16, 2009 19:51 PM
 
Aaron W

Ah, gotcha. That makes sense. Thanks! This was a fun read. :) I ended up telling my wife all about it over lunch.

Apr 17, 2009 09:13 AM
rating: 0
 
SirVLCIV

Yeah, I'd rather compare Cliff Lee in 2008 to Cliff Lee in 2005 and 2006, rather than 2007 (his awful year).

Apr 16, 2009 18:47 PM
rating: 0
 
BP staff member Eric Seidman
BP staff

As I just responded above, comparing Lee to his more effective seasons is fine... there is nothing wrong with that... but the goal here wasn't to strictly compare 2008 Cliff Lee to 2007 Cliff Lee.

The goal was to research how often pitchers have experienced such drastic rate shifts in the same season and then how they have fared in subsequent seasons. Lee was just the baseline of the idea since it happened to him so recently and many chalked up his dominant season to such an incredibly low BB rate and much higher GB rate.

Apr 16, 2009 19:58 PM
 
gregorybfoley

You're drawing the wrong conclusions from your data. Your data does not indicate that it is very rare for pitchers to sustain large improvements in their groundball and walk rates, it simply indicates that it is very rare for these improvements to occur in the first place. Once the improvements occur, they are fairly likely to be sustained. Out of the pitchers you identified as improving their ground-ball rate significantly, 39% (99/254) were able to sustain that success. Out of the pitchers who you identified as improving their unintentional walk rate significantly, 46% (60/131) were able to sustain that success. These high rates indicate that ground-ball rate and walk rate are sustainable skills. The rare occurrence that you noticed (but mischaracterized) is pitchers ever significantly improving these rates in the first place. Pitchers exhibited large improvements in their ground-ball rates in only 6% (288/5031) of the seasons analyzed. Pitchers exhibited large improvements in their unintentional walk rate in only 3% (143/5031) of the seasons analyzed. These low rates of improvement further indicate that ground-ball rates and walk rates are relatively stable skill indicators.

Apr 17, 2009 08:21 AM
rating: 2
 
breed13

I think a potential issue here is that while these changes are rare, they don't necessarily indicate success...

Looking at Cabrera and Villanueva, they had the requisite improvements in GB% and BB/9, but those markers did not translate into the same type of success as it did for Lee... Part of the difference seems to be in SO and HR rates... Lee's both went down from 2007 to 2008, while they both went up for Cabrera and Villanueva...

This is more speculative, but my cursory glance at the list is that Lee may have been one of the better pitchers on the list in year before his big changes (despite it being a bad year for him in 2007)... I'm sure someone will prove my cursory glance to be lacking... :)

Apr 17, 2009 09:17 AM
rating: 0
 
BP staff member Eric Seidman
BP staff

That's certainly a good point. That's honestly the next step here. First it's important to determine how common such rate shifts are and then evaluate its importance relative to performance. Ultimately, though, so few pitchers in the grand scheme of the sample have experienced rate shifts as drastic as Lee's last season so even if we wanted to determine what made some successful and others not would be invalid because of the small sample.

Apr 17, 2009 10:38 AM
 
gregorybfoley

I'm not exactly sure what Breed meant when he used the terms, "went down" and "went up" but here is the data on K/9 and HR/9 for the pitchers in question in each of the two seasons that Eric looked at.

K/9' K/9'' HR/9' HR/9''
Cabrera 9.5 7.3 0.7 1.1
Lee 6.1 6.9 1.6 0.5
Villanueva 7.8 7.7 1.3 1.5

Lee improved his strikeout and home run rates, while the others did not.

Apr 17, 2009 12:15 PM
rating: 1
 
breed13

In reverse order:

Thanks for clarifying my ambiguity (I meant both improved for Lee and got worse for the others)...

Given the small sample size (i.e., 1 pitcher or even a small handful), what can really be said from these changes for Lee? In other words, several things seemed to change for Lee, and it's unclear why you chose to use GB rate and BB/9, while not including SO/9 (which didn't change by as big an amount) or HR/9 (which did change a lot)...

Of course, it's easy for me to ramble on about what you did/didn't include, while you're doing all the hard work... I appreciate the hard work (and good writing)...

Apr 17, 2009 12:50 PM
rating: 0
 
BP staff member Eric Seidman
BP staff

Breed,

The major reason these two rates were chosen is because they were the most discussed relative to his turnaround. Plenty of articles were written last year about Lee's great season, including one by myself, Normandin and Goldstein, where the gb rate and bb rate were highlighted.

What is really interesting, though, is that if only 10 names were returned while probing for drastic changes in BB and GB rates, what happens if the K rate is added in? I'll check later, but maybe Lee is the only person since 1954 to increase GB rate by at least 8%, decrease bb/9 by at least 1.5 and increase K/9 by at least 0.5 in the same year.

Apr 17, 2009 14:31 PM
 
breed13

I agree that Lee may be the only one... I'll be curious to see the results and whether or not Lee can sustain his improvements... This is really fascinating...

Apr 17, 2009 18:42 PM
rating: 0
 
BP staff member Eric Seidman
BP staff

Thanks for the data mining, Greg, that's interesting! Also, in response to your previous comment, it isn't that I drew the wrong conclusions, but rather that I highlighted the very limited group relative to the sample. What I meant was that in the timespan of 50+ years investigated, the number of pitchers that experienced these rate shifts and then sustained them is incredibly small... relative to the number of instances in which 95+ IP were logged back to back.

As you noted, the rising percentages signal that it was easier for these guys with the shifts to sustain the rates but my overall point is more along the lines of the guys who did so constitute an incredibly small portion of the greater whole. I can see how it would be confusing when I noted that even rarer was the number of pitchers who sustained the rates, but I really meant that relative to the overall sample not just the guys experiencing the rate shifts.

Apr 17, 2009 14:28 PM
 
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