The ATF knew full-well that nobody was going to reveal the actual serial numbers of firearms found in Mexico....when has that ever happened?
Therefore, once a large number of Mexican firearms were being traced back to the US, Holder and Obama would have their case for more gun control.
Yes, a few dealers would squeal about the straw purchases, but the ATF, DOJ and MSM would portray them as part of the problem, as unable to prove their case (no serial numbers) and ignored by the media.
Then...
"Therefore, once a large number of Mexican firearms were being traced back to the US..."
Gee, do you see the fallacy of any argument you may come up with?
Once you make conflicting statements, you veracity is suspect.
I learned that on TV.