Not sure what he's referring to, but during his tenure he decided to "shake things up" and laid people off almost-Elon-Musk-style. He basically had a target in terms of Dollars, and he asked HR to come up with metrics to hit the target. They laid off everyone who had had a bad review the prior year. But that wasn't enough to hit the target, so they laid off everyone who had an average performance review, but low bonuses. But that didn't hit the target, so they offered voluntary severance packages to those who had not had a promotion more than N years. That, along with encouraging early retirement let them hit the target.

The layoffs happened all at once - not in phases. You had cases where a manager was suddenly told to inform his report that he is being laid off, only to then be told that the manager himself is being laid off.

As you can imagine, any time someone does a blunt top down approach like this, you lose a lot of critical people with no one in the team knowledgeable to take over.

No one saw it coming. Managers were not told in advance.