Occassional thoughts about orienteering

Thursday, April 20, 2006

Cool baseball graphics


No orienteering today. If you're not a baseball fan, don't even bother reading further.

Win Probabilities

Some baseball geeks have been looking at how the probability of winning a baseball game changes as the game situation changes. They've reviewed loads of past games to come up with things like:

88 percent of the times a home team is ahead by 2 runs in the 5th inning, with no outs and a runner on first, the home team wins. But, if the home team is down by 2 runs, the expected winning probability is just 34 percent.

You can describe any situation in terms of the team (home or visitor), inning, number of outs, number and position of baserunners, and score difference.

You can try yourself by looking at an online win expectancy calculator.

You can track the progress of a game by tracking the changes in win probability throughout the game. It is a bit like the split graphs you can get for an O' race through Attackpoint or Winsplits.

Here is yesterday's game between Kansas City and Chicago.

The graph is a picture of the flow of the game. You can see that Chicago quickly took charge when Cintron scored in the first inning. The game moved along pretty evenly, but with Chicago ahead by a run, until Chicago scored 3 runs in the middle of the game. Uribe's home run made the graph jump up. From then on, Chicago and KC played fairly evenly, but time ran out on Kansas City.

As you play around with the win expectancy calculator and look at graphs of different games, you get a feel for how to read the game by looking at the graph. Just a quick look at a graph gives you a feel for how the game went.

The graph above is from www.fangraphs.com where they track win expectancy for every major league game. Point your browser there and check out a few games for your favorite team.

I first came across these win expectancy graphs in a book called The Hardball Times Baseball Annual 2006 - a book I recommend to geeky baseball fans. It seemed like a cool idea, but it also seemed like a bit of work to track win expectancy for a lot of games. I'd planned to track the Kansas City team by calculating win expectancy at the end of each inning (which is not much work), when I discovered the fangraphs.com graphs.

If you've read this far, you must be quite interested. If so, you should check out Dave Studeman's article on win expectancy graphs on The Hardball Times web page.

Ok, ok, here is some orienteering

I'm supposed to write about orienteering everyday. So, let me just suggest that you check out Eva Jurenikova's maps from last weekend's races in southern Sweden. Look for the news item from 2006-04-20.

posted by Michael | 9:09 PM


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