This idea started as a conversation on Twitter about having the bases loaded with no outs but failing to score a run:
Honestly I was pretty surprised – 16% sounds a bit high to me. But I was also curious about what Andy asked. My hypothesis was that it would be going up in recent years since the strikeout rate has been going up (which is very helpful in getting out of these situations!), but the handy baseball win expectancy finder didn’t have run expectancy data by year.
So after a bit of coding I added that to the site, and ran an analysis. And here are the results: (raw data in this Excel file)
I added a rolling average (the blue line) because this only happens ~600 times a year so the data is rather noisy. Anyway, the percentage has indeed been going up lately, although it was even higher in the 1960s when total offense was down. The minimum percentage is 12% in 1994 (in the steroid era), and the maximum percentage is 20.5% in 1967 (right before the Year of the Pitcher!)