It’s been a while since I’ve thrown a sop to my baseball-oriented readers and the season is under way, so I’m gonna make it up to you with a new statistic, because the one thing baseball suffers from is not enough statistics.

I was trying to explain the game to an Icelandic friend of mine the other day. What’s with guys charging the mound? he wanted to know. (This from a hockey fan.) Well, they get upset when pitchers throw at them, I said. So why do the pitchers throw at them? he asked. To instill fear, I said. It’s a lot harder to hit when you’re worrying that the next pitch might come at your head. Don’t pitchers get thrown out for doing that? he asked. Yes and no, I explained. It’s complicated. He asks, can’t they at least keep track of the pitchers who do it all the time and punish them later? Why yes, I mused. Yes they can. And then and there I conceived the VI, or Viciousness Index.

VI relies on the premise that a pitcher’s true wildness can be roughly judged by the number of walks he allows. The fewer he allows, the better idea he has of where the ball is going most of the time. So if he allows very few walks and still hits a lot of batters, the way Pedro Martinez does, one can assume that it’s not entirely or even mostly by accident. Therefore VI = HBP/BB. I submit this will prove an excellent index to pitcher viciousness.

I’d like to oblige you with some actual numbers, but HBP pitcher data turns out to be scarce. It’s not in the Lahman database, Baseball Reference doesn’t have it, and that means I don’t have it either. In lieu of numbers, I offer two hypotheses. First, pitchers with headhunting reputations, like Bob Gibson and Don Drysdale, will have high VIs. Second, the VI leaders, seasonally and career, will be a better set of pitchers than the VI trailers. (This is of course largely because the trailers walk more hitters. A stronger version is that if you match pitchers with similar walk/inning ratios, the ones with the higher VIs will tend to be better.) If somebody out there has HBP data for pitchers and wants to share it with me so I can confirm or deny, I pledge that I will not only publish the lifetime and 2002 leaders for the Viciousness Index, but I will add the data to my pitching search engine. Now is that a deal or what?

(Update: I’ve mentioned before how impressed I am with my commenters — it’s a regular little salon around here — but Greg Padgett has outdone himself. He actually grabbed the HB numbers from the Yahoo MLB database and posted the VI leaders and trailers, both raw and adjusted, for 2002 in the comments. He also extracted a few VI comparisons for pitchers with similar walk rates. I’ll have more to say about this later, but on casual inspection the results are inconclusive. There are some excellent pitchers at the top, like Pedro Martinez, Brad Radke, Derek Lowe, and Mark Mulder, but there are some pretty good pitchers at the bottom too, like Bartolo Colon and Jason Schmidt. Each end of the list has its share of washouts too. I suspect career results will be more conclusive, since we’re dealing with a relatively rare occurrence. Adjusted VI doesn’t range much beyond plus or minus 5 in a single season. But go read Greg’s comment.)