ClemsonTexan
Waterboy
but why not a three-step drop? etc. etc.
It's already been explained that a 3-step drop is for shorter routes such as slants, hitches, outs, etc. If you have a Tyreek Hill or Jerry Jeudy, or better yet, a DeAndre Hopkins, who can take a slant to the House, then it's not a bad play call. But in a situation where you need 11 yards for a first down, you are not going to call a play that is going to net you 6.
So that is the logic behind calling a longer pass play. You are playing to get the first down. And you might as well because whether you're punting from your own 5 or your own 11, your field position is going to suck either way.
Now I know the 20/20 hindsight brigade will say "you don't pass from your own end zone, you dummy!" But this literally happens all the time. I'm sure it's not even the first time it's happened with Watson under center.