It's categorically not true that only low performers are affected. There's really more than one event going on simultaneously here. Some of this is about cost cutting in metro locations, some of it is department-based based on specific circumstance, and then they've also taken the opportunity to add in the usual yearly low performer RIF.
Though having seen the forced ranking system throw many perfectly fine people under the bus over the years, I'm very cautious about believing any "low performer" label in general.