For the 2+ GoG times, here are the stats for the past 4 years.
2013: 14 of 18 DNF'ed (78%)
2012: 8 of 11 DNF'ed (72%)
2011: 11 of 19 DNF'ed (58%)
2010: 8 of 21 DNF'ed (38%)
The trend is a a very disturbing one. While in 2010 only 38% dnf'ed, in 2013, an astounding 78% did. If you look at the results by qualifying time page, it is a very dramatic change right at 2 hours for that race. It is like somebody flipped a switch. It is not the 2:15+ crowd that is dragging the pack down, there were only 4 of them this past year (one finished, the other 3 dnf'ed).
I wonder if the problem was that the 2:30 GoG time requirement was giving folks a false sense of security. Some of them may have thought that if they were in shape enough to make it 10, 15, or 20 minutes under the cutoff then they were on track to finishing the PPA.
Oddly enough, from looking over the past few years, the other group that has a high DNF rate are the PPA vets with a time in the 6:00 -> 6:20 time range. Once again I suspect that many may have approached the race with the "I had lots of cushion last year," and paid the price for it. The 6:20+ qual time folks knew that they had to step up their game or risk DNF'ing and oddly enough, many of them finished faster than before, several cutting some serious time off of their previous efforts.