Yea I read it

The linemen of some teams that use zone blocking schemes have been criticized for their penchant for cut blocking the knees of defenders, sometimes away from the play. Cut blocks are illegal when a defensive player is engaged by another offensive player. Although some consider the technique unsportsmanlike because of the risk of serious injury, when taught and applied correctly it is a very effective tactic. In fact, some defensive players employ the technique to eliminate blockers so other defenders can make the tackle.