Ask any NFL defensive back about the spike in ACL injuries this season. He will attribute it to defenders having to aim lower to make tackles and avoid a suspension for hitting a ball carrier too high.
However, that doesn't explain the injuries to players like Indianapolis Colts wide receiver Reggie Wayne, who was uncovered when he twisted his knee and tore his ACL earlier this season.
The increase in ACL injuries has been documented recently by ESPN's research department.
-- Bill Bradley, contributing editor