The 5 percent rule


Joe Posnanski over at Hardball Talk with a piece titled "The Timeless Game (and, maybe, the myth of closers)":

There are two baseball phenomenons that are fascinating me these days. The first I’ve written about before: Teams leading going into the ninth inning have been winning 95% of the time more or less since the dawn of time. Yes, strategies change. Players change. Equipment changes. The use of relief pitchers evolves, the preparation of hitters evolves, the data used to set up defenses evolves, the game itself evolves.

In 1948, teams won 738 of 776 games they led going into the ninth. That’s 95%.

In 1968, that crazy year of the pitcher, teams won 1,315 of the 1,381 games they led going into the ninth. That’s 95%.

In 1977, when I was 10 years old and Duane Kuiper hit his only home run, teams won 1,788 of their 1,876 games. That’s 95%.

In 1989, when reliever Mark Davis won the Cy Young and Tony La Russa and Dennis Eckersley ushered in the era of the one-inning closer, teams won 1813 of 1890 games. That’s 95%.

In 2000, when the home runs were flying like balloons before a Super Bowl, teams won 2,081 of 2,190 games. That’s 95%.

Last year, teams won 2,032 of 2,137 games. And that too is 95%.

As Posnanski pointed out, nothing new there. He's written about that before; we've written about it here at ESPN. Joe also points this out, however:

So, sure, the quality start HAS to be way, way down.

Except ... it isn’t. Like with the ninth inning win, there a consistent statistical rhythm to quality starts. It’s not quite as consistent, but it’s close. Since the beginning of the live ball era, these two things have been true:

– About half of all starts end quality starts (that is: six innings pitched, three earned runs or less).

– Teams that get a quality start win about two-thirds of the time.

The timeless game? Indeed.