Nothing New To See Here
I was one of the ones that fell victim to this last year. I'd had excellent reviews and had been granted a significant amount of stock options in the previous round of salary increases. Got the call with my boss and HR to tell me I was put on notice, then at the end of that week headed off on Garden Leave. There were no other jobs that were suitable so I took the package and left.
It has nothing to do with performance or ability, often its just a "wrong place, wrong time" situation.