Harlon Barnett is the Associate Head Coach and Safeties Coach at Northwestern. When this clinic was filmed, he was the Defensive Backs Coach at Michigan State.
The video on this post is taken from Coach Barnett's Glazier Drive 9 Video Defensive System "Harlon Barnett's DB System."
The three techniques in the system are: wBoss, Crack the Cracker, and Shock & Shed.
Defensive backs have to know how to take on a block by keeping their hands inside, locking the blocker out, and getting rid of him.
The boss drill is to work on an outside defender who has the edge and needs to keep the edge. The technique is to attack the blocker with the inside shoulder, while keeping the outside arm and leg free.
Crack the cracker is the technique to use when the block is coming from the outside and from a receiver. The DB needs to stay square and use a similar technique with one arm to the boss drill.
Shock and shed technique is applied when the defensive back is more head up on the player coming to block him. The player with the hands inside and the lower pad level usually wins. The technique is to get the hands inside, lock the arms out, control the blocker, shed the block, and go make the tackle.