@Zeppelin7, if you read the College Board’s explanation, the cutoffs are established using advanced statistical analysis intended to account for differences in difficulty from year to year. See http://apcentral.collegeboard.com/apc/public/courses/11583.html. So if the cutoffs were higher this year, that means the College Board viewed this exam as simpler than the last Physics B exam.
In order for the AP distribution to have been the same this year as last three things would have had to occur: (1) the pool of students taking the test must have been of the same ability (and maturity), (2) their teachers must have been equally able to prepare them for the test, and (3) the statistical analysis used to equate and scale the test to prior tests must have been accurate.
Personally, I don’t attribute the problem to (3). The College Board has a lot of experience in doing this type of statistical analysis. It is the heart of literally everything they do. They could have made a massive error here, but it is unlikely.
Further, AP Physics 2 had even higher cutoffs for those who passed:
5: 73%
4: 61%
3: 42%
2: 23%
And yet, the students who took that test had a far more normal distribution of scores:
5: 8.4%
4: 14%
3: 32.8%
2: 34.9%
1: 9.9%
I’m no expert, but I think it is far more likely that the primary culprits are (1) and (2), i.e., an overnight expansion into a large student population that was too young and/or inexperienced to take this class/test, and a teacher population that was not properly trained to teach it.