The great debate of "What's the percentage chance a leadoff walk will lead to a run?" came up at a recent Spinners game, and I just did some research to find out.
Someone actually studied 10 seasons of Red Sox games and (among other things) found that any time a Red Sox batter walked to lead off an inning, there was a 42% chance that he would score. For opponents, the percentage was a statistically similar 41%.
That still doesn't answer the question of what the chance is that any run would score in that inning...I have no idea what that is, I just know it must be greater than 42%, even if not by much.
The moral of the story is that leadoff walks are a great thing when you're up and cringe-worthy when you're in the field.