Look at a longer view. This is just for 1310 PILOTS:
FY09 508 IZ, 420 selected (23 AZ) 82.68%
FY10 428 IZ, 359 selected (3 AZ) 83.88%
FY11 473 IZ, 378 selected (2 AZ) 79.92%
FY12 338 IZ, 282 selected (2 AZ) 83.43%
FY13 511 IZ, 342 selected (5 AZ) 66.93%
FY14 450 IZ, 295 selected (19 AZ) 65.56%
FY15 571 IZ, 321 selected (20 AZ) 56.22%
The number of folks IZ matters. The number of 1310's selected this year isn't out of the norm. Whether that was an adequate number to feed the DH/CDR CMD machine is another discussion.
Break break
I remember Detailer briefings WAY back in 2004 telling us that the bureau wanted to move the hard screen up to O-4 and the DH board. The feeling then was that too many folks were getting just a ticket punch DH tour and the O-5 board & CDR CMD boards were major bloodbaths. The bureau was of the opinion that this was too late in the career path for a culling, so they wanted to move the "hard" screen to earlier in the Aviators career path. They seem to have been successful. This, along with over accessions in the 04 YG has caused a perfect storm.