Not a stupid post at all. I don't think they have necessarily tried to get rid of their best employees, but from what I've seen it's all been about age; good, bad, average, didn't matter, the older you were the less you were welcome in the "new and improved" SF.
As far as people leaving on their own because of work conditions, I'm sure there has been adverse selection. The better you are the more likely you have other options. So from the group of people just leaving for something better, they have likely lost more good employees than bad. From the "structure study casualties" they've lost a lot of experience, salary, and both good and bad. I've seen zero effort in the structure study groups to retain strong employees, even ones more technical in nature.
I think they are just trying to get to a bottom line number for non executive employee expense. I'm not sure what that number is, but it probably something along the lines of 70% of base year 2017.