Until 2009, I was employed by IBM for over 30 years. For those that don't know, since the mid-1990's, IBM has laid off tens of thousands of people in wave after wave of layoff's. Layoff's at IBM have been and continue to be an annual event since 1999.
I can tell you that most cuts made no sense what-so-ever. Those that everybody knew should be gone, stayed. Those that thought hi-performing people would never be let go, were shocked when they saw them go. I personally know a man who currently has over 40 years of service at IBM. Everyone that knows him agrees he should have been let go 20 years ago, yet he's still there with absolutely no plans to leave. Another man I know is a highly valued employee who has raised his hand and wants to be let go (so he can retire with a severance package) should there be a second round of layoff's this year. He was told by his manager that "It would be hard to justify that to upper management."
I can also tell you that severance packages grew less and less generous with each new round of layoff's. Two years salary for anyone let go back in 1999 was the norm. Today, it's two weeks pay for every year of service, to a maximum of 26 weeks weeks pay. If you have a low performance rating, it's 3 months salary - maybe! They approach low performers and ask them to voluntarily leave with 3 months pay. If the low performer refuses to leave, they'll be put on a PIP (which they don't have a prayer of making work) and after 3 months if they haven't improved their performance, (and they wont improve it because their management will ensure they don't) they're fired with zero severance.