I'd argue low performance is apart of the culture. Going along to get along is rewarded from what I've seen and that means, not ruffling feathers or being creatively "disruptive". That sort of of status quo, regimentation causes lifeless "performers" to really "shine". It exposes people who don't belong and some of those "outsiders" get put out with the surplus. This is going to be a fascinating uncovering.
Yes the nps internal survey and the rating structure is mired down in old school of thought re: finding, rewarding and growing talent. T loves Harvard business review and there's so much research put out by them to suggest a major revamping needs to take place. But that would require a cultural revolution that t can't pivot to. The money, the innovation etc, this thriving software company - is in healthy culture.
And culture is something that I think any behavioral management consultant would blame on the c suite and Randall mostly, for thinking that he could pivot this company without making meaningful systemic and core changes.
As for pay and comparable jobs, that hasnt really been the case from the people I know from the last two rounds of surplus. They've mostly gone on to earn more money (esp. The ones who were targeted because they were outside of the box". There is even a thread here re: that. I do believe that the low performers and those who thrive in t's culture won't fare better as you suggest, due to the false sense of productive meaningful work that t perpetuates. People who are rewarded to go along to get along, won't make it in this changing economy.