As with any rule, when interpreting it, start with the reason the rule was enacted. As part of its overall risk minimization strategy, the NF eliminated all low blocks except those that they deemed at low risk of injury. The reason for the FBZ initially, and this change requiring “immediate” contact, is that it was felt low blocks occurring before the parties could generate enough momentum to raise the incidence of leg injuries were an acceptable compromise that struck the right balance between offense and defense without causing serious injuries. Now, as the tolerance for risk gets even lower, and it has become clear that offenses don’t need the help, use of low blocks has been restricted further.