Q,
Remember, we are talking about the Department of Homeland Security here - possible the most inept department of all.
They couldn't organize the proverbial piss up in a brewery!
It is far more likely that their figures are just incorrect or they have not included some for reasons of their own. They certainly do not report all visas in all sub-categories.
The figures also include Consular Processed cases, so they could have just misreported those.
In any case, the Department of State is the final authority on the number of visas issued, so no amount of pressure is going to change the lack of spillover.
Time to take the tin-foil hat off. :D
Let's not forget, it usually takes USCIS until July or August to provide DOS with the final figures to set the annual limits, so maybe it will change, but I doubt it.
The DHS Report is usually published much later than this - now I understand why!
PS Q, It really isn't worth disagreeing over. I do get frustrated at the amount and quality of data presented. Read my comments with that in mind. :)