When you are the QB, you can throw the ball two different ways: straight (hold the button of the receiver you want to throw it to) and up high (press and release the button for that receiver). When you throw it up high, the QB will throw the ball over the safety to your receiver. He will catch the ball most of the time. Throwing it straight is the most common way. He just throws it to the receiver and it will not go over the safety. It is best to use the straight pass if the WR is wide open.

Throw the ball to any receiver. After the ball has been thrown, switch into your intended receiver and let the CPU run the pattern. Immediately before the ball gets to you, tap R2 + L2. If the ball is somewhat to the receiver, he will reach out and most likely catch the ball.