Cover 2 is relatively simple. Starting with the Linebackers. OLB will drop to the curl unless there is a number 2 wide receiver. (Tight Ends do not count.) If there is a number 2 wide receiver, the OLB will wall the number 2 receiver to the outside. Mike Backer will wall the Tight End toward the outside. Basically, all linebackers want to play a "trail technique" . They have to play run first. This means they will be almost chasing the receivers. This will put them between the QB and Receiver. This is good because the QB will have to throw over the linebackers. By throwing over the LB, the ball has to stay in the air longer which will allow the safety to make a play on the ball. The corners are doing the opposite, they want to keep everybody to their inside. They squat and keep outside leverage. They are looking inside at the QB. If the ball is not in the air on the QB's third step, they immediately open and run to the deep out squeezing the passing lane. As you can tell the philosophy of cover 2 is to funnel everybody to the safetys who are aligned up on the hash. You want to keep all the receivers outside the hash. Also do not worry about the short stuff. The defense must rally to the ball and punish the receiver so he will think twice about catching the ball underneath.