# Defensive Efficiency Ratio (DER)

### Definition

Defensive Efficiency Ratio is a statistic used to evaluate team defense by finding out the rate of times batters reach base on balls put in play. Basically, for every ball hit into the field of play, how likely is the defense to convert that into an out?

The formula for Defensive Efficiency Ratio is: 1 - ((H + ROE - HR) / (PA - BB - SO - HBP - HR)).

Defensive efficiency is a very good tool for assessing team defense, but it has its flaws. For instance, a team whose pitchers allow a high frequency of hard-hit balls will most likely have a lower DER because those balls are more likely to wind up as hits. There is also nothing in the equation that factors in luck or the ease of a team's defensive chances. But over a large enough sample size, this concern is mitigated.

### Fantasy advantage

Fantasy owners can use DER as a tool when selecting starting pitchers for their active lineups. Pitchers in front of strong defensive squads have a better chance to limit runs than hurlers who work in front of weaker units.

##### In A Call

"defensive out percentage"