Was a direct result of the new 'targeting' rules.
Defenders are so concerned about going high, they now are forced to go low.
This is just the beginning, you will see many more big time receivers go down due to knees getting chopped.
Defenders have no choice.
Wait, the NFL will change the rules to you can only hit between the waist and shoulders, and the 'N' in NFL will be changed from National to Nanc-boi