Why on 3rd and 1 or 2 when teams line up in a passing formation do defenses so commonly line their DB's up 5-10 yards off the WR? In doing this, they are just basically saying "here, take this free first down". This just popped into my head because Wyoming just had a 3rd and 1 against Fresno St. and Fresno had their DB's WAY off the WR's. I just don't understand it.
I guess some would say they are trying to prevent getting beat deep, but I would rather risk getting beat deep than just guarantee them a free first down.