Tuesday, 24 March 2009

Runs/Wickets State 3

As stated in the last post, the problem with looking at a single innings in isolation is that it does not take into account the match situation. Mitchell Johnson may have been improving Australia's chances of winning the match, but did they have much chance to begin with? For that, we need to look briefly at South Africa's second innings.

When the ninth wicket fell, the chances of South Africa winning, based on previous results were about.667—that is, two-thirds of all matches where the team batting in the second innings stood at 637/9 ended up with that team winning. However, there had been no matches that had seen the second innings finish on 651. Thus, at that point, we go with the available data, and wait on the outcome.

When the fifth Australian wicket fell, their chances of winning were .288-.667=-.379. When the tenth Australian wicket fell, we learned that the 422 score in the second innings results in defeat 2 out of 3 times. Australia's chances of winning were .333. South Africa's chances of winning on 651 go up to 1.000. They are the only team to reach that score at the end of the second innings of a match. However, the net effect of Hilfenhaus losing his wicket took Australia from -.271 chance of success to -.667, or a swing of -.396. But it would be unfair to pin all that blame on him. We need to share it out among all eleven players. Cricket is a collective effort, Mitchell Johnson gets the same blame for falling short as Hilfenhaus. Everyone gets a reduction in their score of -.032. The table produced yesterday now looks like this:

Johnson +.109-.032=+.077
McDonald +.101-.032=+.069
McGain +.014-.032=-.018
Siddle -.007-.032=-.039
Hilfenhaus -.032

Just because Hilfenhaus' was the last wicket to fall doesn't mean he deserves all the blame. Siddle's wicket was actually more significant in leading to a defeat. McGain's performance goes from being a positive to a negative.

One could argue that we need to adjust South Africa's score for Australia's first innings. I'm not sure. We'll take a look at that another time.

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