Pitches per inning pitched is a tool used to evaluate how efficient a pitcher is at getting his outs -- or how many pitches he typically needs to use to do his job. Calculating the number is easy enough. It's found by dividing a pitcher's total number of pitches thrown by his total number of innings pitched.
It's extremely important for starting pitchers to keep their P/IP somewhat low, so they can work deep into ballgames -- and, as a result, take some of the strain off their relievers. However, some pitchers can be very successful despite high P/IP rates -- generally power pitchers who have tendencies toward walks and strikeouts. P/IP isn't quite as important for relievers -- especially specialists or relievers who generally don't throw more than one inning.
Pitchers with the game's best P/IP rate typically average fewer than 15 pitches per inning. A starting pitcher with those numbers would be able to go seven innings on fewer than 105 pitches.
In A Call
"pitches per inning," "pitches per out" (multiplied by three)