I do this a lot. I hot route my fastest WR to a fade first. If they're showing blitz from the safety on his side, then you know you're gold. Otherwise, after the snap i see where the safety's going. If its not to cover my guy, i give the WR a little time to get separation. Then I tap his letter (symbol) and press up on the left stick. Most times he catches it. This works best if (of course) the CB isn't blazing fast. Keep in mind your QBs throw power when deciding where to throw it. If its in the 90s, you can make a huge play. Its good to try to set this up prior with some underneath throws and/or some successful running plays. A playaction helps it work too.