The impact of NFL kickoff rule changes on player injuries: Forgoing excitement to reduce injuries?

Recognizing the increased danger during kickoff returns, the National Football League and National Collegiate Athletic Association changed rules aimed to reduce player injuries. Using a two-stage model, we examined the impact of rule changes on kickoff returns to the rate of player injuries. We estimated the impact of the changes on the number of kickoff returns using a difference-in-difference approach; from these estimates we created an instrumental variable measuring the local average treatment effect of the NFL rule change on player injuries. Our findings suggest that moving the kickoff location decreased both the likelihood of kickoff returns and player injuries.