Monday, August 25, 2008

The Changing Historical Relationship Between Walks, HBPs and HRs

Since I posted something on HBP's last week, I thought I would post a couple of items that I put on the SABR list last year. Here they are.

As many of you probably know, the HBP rate has been on a general increase for many years (since about 1980). But one thing that could account for it is that pitchers have poorer control than they used to (I am not saying that they do-just that it could be a reason for the rise in HBP rates). So I thought that it might be useful to look at the HBP-to-walk ratio over time. I created 4 graphs and they are at

There is one graph for each league. The first one is the HBP-to-walk ratio using all walks and the second one excludes intentional walks (they were not officially recorded until 1955). I also started the NL in 1897 or so because it did not look like all of the HBP were recorded by then. The file is a Microsoft Word file so when you click on it you might be asked to open it in that program. You will have to say yes.

Both leagues were around .16 about 1900. That is, there were 16 HBP for every 100 walks. But by around 1940 or so, it was 4 (or fewer) HBP per 100 walks. For both leagues, the rate has been rising since 1980. This suggests to me that the higher HBP rates these days is not due to poor control. There may be other issues involved so we might not be able to conclude that.


Yesterday I discussed the HBP rate relative to the walk rate and how HBP/Walks has risen over time. But I also thought about how HRs might affect this. If a player hits a HR, the pitcher might want to pitch inside more to that player or anyone else on that team. This could lead to more HBP. Maybe even sometimes pitchers intentionally try to hit someone because of HRs. So I looked at HBP/HR over time. Since 1920, in both leagues, the rate has pretty much stayed under .5. But, of course, control is an issue, too. So I figured out the non-intentional walk rate each season since 1955 for both leagues and then the historical average from 1955-2006 in both leagues.

For each league/season, I then divided the non intentional walk rate by the average over the 1955-2006 period. If a league/season had a rate that was 10% higher than the historical average, then they got a 1.10. The HBP/HR rate for that league/season was divided by 1.10. So I deflate the HBP/HR rate by 10% since that league/season's pitchers had control that was 10% worse than average, which could partly account for a higher HBP/HR rate. So I did that for all league/seasons. The new number is called the adjusted HBP/HR rate. I graphed this for each league since 1955. The two graphs are at

The file is a Microsoft Word file so when you click on it you might be asked to open it in that program. You will have to say yes.

What I see here, is that if you adjust for HRs and control (as measured by the walk rate), is that pitchers today seem pretty willing to hit batters. Does this mean that they are willing to pitch inside and that the high HBP rate is a side affect of that? We probably can't tell for sure since we don't have stats on how many pitches are thrown inside. But certainly pitchers today are willing to hit batters. In the AL, each of the last 6 seasons is above the historical average of my adjusted HBP/HR rate (which is about .27). In the AL, 5 of the top 6 seasons in the unadjusted HBP/HR rate were from 2001-05. 2006 was the 11th highest.

In the NL, the historical average of the adjusted HBP/HR rate is also about .27 and each of the last 6 years is above that. 6 of the 10 highest unadjusted HBP/HR rates were from 2001-06. One of the reasons I looked into this issues is that it came up at the most recent SABR convention. There was a panel on St. Louis baseball and the former player all said that pitchers today don't pitch inside enough, that they leave the ball out over the plate too much and that they are reluctant to hit, or be aggressive with guys who are hitting HRs. Based on what I have done, this does not seem to be true.


TwinsFix said...

Excellent stuff. Very good research and very interesting!

Cyril Morong said...


Thanks for dropping by and the compliment. Glad you liked it.