So, chest thumping aside, there's a bit of a difference here between us/this situation and the target population in question to the FBI which probably isn't evident to anyone who isn't familiar with our job and that "practices between quals" for the FBI may mean a few months, whereas for us it could literally be 4-6 years.
There's a lot to unpack there and it isn't a 5 minute conversation, but the tl;dr is that if you change the standard (for the better) but don't provide any mechanism of retraining to maintain that standard compared to the standard they've been held to for however many years, then it's entirely foreseeable that this would happen to a subset of your manpower.
If anyone wants any further thread drift on the topic, please ask a mod to split it off to a new thread.