Is defense or offense more important for professional football teams? A replication study using data from the 1998-1999 regular football season

The purpose of the present investigation was to replicate Onwuegbuzie's 1999 study by identifying which variables best predict a team's winning percentage in the 1998-1999 regular professional football season. Findings gave a model containing five variables: (1) turnover differential (which explained 54.4% of the variance), (2) total number of rushing yards conceded by the defense (which explained 21.3% of the variance), (3) total number of passing first downs attained by the offense (which explained 9.4% of the variance), (4) percentage of third-down plays that produce a first down (which explained 4.1% of the variance), and (5) total number of penalties conceded by the opponents' defense resulting in a first down (which explained 4.1% of the variance). These variables combined to explain 93.3% of the total variance in winning percentage for the 1998-1999 season. That the first two variables, which explained more than 75% of the variance, were characteristics of the defense supports Onwuegbuzie's conclusion that defensive gains are better predictors of success than are offensive gains.