Your problem is that you're looking at only numbers and not the psychological impact of the moratoriums. It would be the same type of impact as suddenly announcing a truly viable and affordable alternative energy source.
Agree Vel, I think that psychology does play into the equation, and could even sometimes serve as a "spark" to ignite an oil $ decline (the one in 2008 was well overdue as gas prices had spiked to unreasonable levels in the months prior, and the economy was slowing
dramatically). But again, I think it was underlying economic situation (halting economy) that fostered the steep temporary decline in oil prices in 2008, and not simply the announcement that the President would support lifting the moratorium. It may be the spark, but if there's nothing of substance there to keep it burning, it will simply fizzle out after a few days and any price shocks would normalize and there would be no change.
Again, there's just not enough substance around the lift of the offshore moratorium to drop prices by anything dramatically. The yield is much, much too small to have any huge impact.
For instance, do you honestly believe that if Obama would announce today that he would lift the moratorium on offshore drilling, gas would fall by $100/barrel again? That just doesn't sound reasonable to me.