Measuring Risk in NFL Playcalling

Coaches in the NFL make approximately 1000 offensive play calls during the regular season. These calls are the result of countless hours of preparation and analysis and the coach's own personal experience and each coach has their own measures of success and biases regarding types of play calls. What has not been utilized previously is a systematic analytical approach to measure a play's outcome in relation to the drive, and an evaluation of whether coaches' are irrationally biased in their playcalling. Using play by play data from the 2005 through 2008 NFL regular season, an evaluation system is built around the concept of expected points. Expected points have been used in baseball for over 40 years and have been applied occasionally in football (Romer 2003; Carroll et al 1988). This framework allows for a true calculation of risk for different play types. Risk for passing plays is found to be lower than risk for running plays in certain situations, while still yielding a higher expected value. These results confirm previous analysis (Alamar 2008) that teams underutilize the pass.