Failed VDB today, what did I do wrong?

Occasionally -- it's rare, but it does happen.

Once during IROPS very late one night at ATL (our plane wasn't even there yet) the gate agent took advantage of a lull in the cacophony and processed our VDB paperwork.

Usually the gate agents aren't going to have time to do a bump early -- an overbooked flight also means a full flight with all the usual business to attend to. I've seen a couple so busy that they didn't even have time to ask for volunteers, so even if you think you're way too late, it never hurts to go up to the podium & ask.

One caveat: If you do find yourself the beneficiary of such an early VDB, it's best to remove yourself from the gate area graciously but expeditiously. There have been a few reports of such VDB's being rescinded if they turned out not to be needed and the recipients were still hanging around.

I think this is unique to Delta, there is no broader industry wide differentiation like this between the terms overbooked/oversold at many carriers, but this post here from a waaays back has some more detail on the differences:

http://www.flyertalk.com/forum/600993-post3.html

Each flight has an overbooking profile. At your typical major carrier, revenue management uses (usually quite sophisticated) modelling software that analyses historical patterns and the level of no-shows or last minute cancellations for that flight. There can be marked differences in overbooking for flights departing out of a hub (potential for misconnects) versus the inbound spoke departing from an outstation going in TO a hub (no misconnects).

There's also regional variations and anomalies on International routes. Flights in and out of India are frequently oversold by as much as 100 on a widebody aircraft from say DEL-LHR.

Some carriers are definitely better than others at managing the overbooking profiles. For instance, some carriers will manually over-ride the overbooking profile during Thanksgiving or Christmas when there's a high percentage of leisure travel, not many no-shows, and where there's very little "slack" to re-accommodate displaced passengers from misconnects or cancelled flights etc.

Also, some carriers have a "no overbook policy" for premium cabins and only oversell the main/Y cabin, yet others like UA will often overbook the J cabin on Japan flights by up to 6 seats.

There are also the occasional rare "holy grail" flights that seem to somehow slip through the computer modelling, and are consistently overbooked and consistently need VDB's. I remember a BD flight in the UK from LHR-DUB on a Friday around 7pm which was always oversold, and I actually knew people who'd regularly book several weekend trips to DUB when seat sales were being offered, knowing that they'd get the option to VDB on as many as 2/3rds of those flights and make out handsomely.

I also had a VDB processed early. I had a MSP-ORD-somewhere booked and saw MSP-ORD was Y0 and I enquired at te Ga! She said YES gave me a $200 and booked me on the direct flight to "somewhere"

Worked well for all involved