New rules are going to lead to more injuries?

I blogged last week about the new rules in the NFL and NCAA that are targeted at preventing football players from hitting their opponent in the head or leading with their head when making a tackle.  The purpose of these rules is to cut down on the number of head and neck injuries.  I've heard some commentary recently on ESPN from former players saying that these rules will cause an increase in the number of knee injuries.  They think because defenders cannot tackle offensive players by hitting them in the head, they will now target their knees, because they don't have any other option.  Now, I didn't play football, or coach football, but it seems to me like there are a lot of other options besides hitting a player in the knees or the head.  I know when I was working as an athletic trainer with the football teams at Southern Miss and Auburn the players were not taught to tackle by hitting in the head or knees.  They were taught to hit a player in the chest or middle of the body and then wrap them up.  I think there are other options for tackling besides the head and the knees.  It may take some adjustments, but I don't think these new rules should cause a huge spike in the number of knee injuries.