Defense independent pitching statistics

In baseball, Defense Independent Pitching Statistics (DIPS), also known as DIPS ERA (dERA), is a sabermetric statistic which measures a pitcher's effectiveness based only on plays which are completely under his control: home runs allowed, strikeouts, and walks. Those plays are under only the pitcher's control in the sense that fielders have no effect on their outcome. There is a little to no difference in the abilities of Major League pitchers to influence the rate of hits against them on balls in play. Sometimes a pitcher who has the one of best out percentages on balls put in play one year, the next year will have one of the worst.

Voros McCracken was the first person to publish these findings on the Internet and is thus given credit for formulating them.

Complicated regression calculations were done using play-by-play data for every single MLB game from 1973 to the present, and from that data this equation was derived:

In that equation, "HR" is home runs, "BB" is walks, "K" is strikeouts, and "IP" is innings pitched. That equation gives you a number that is nothing close to a normal ERA, so the equation used is more often (but not always) this one:

That equation gives a number that is much closer to a potental pitcher's ERA.

DIPS ERA is not as useful for knuckleballers and other "trick" pitchers. Recent research indicates that pitchers with extremely slow changeups are systematically underrated by DIPS ERA, although the validity of this research has been questioned by some.

The work done by McCracken and others on DIPS is regarded by many in the sabermetric community as the most important piece of baseball research done in many years.

See also

• Baseball statistics