It might be house-cleaning. I think some companies are doing layoffs right now that don't really need to because it's one of the few times where you can get rid of a lot of dead wood and come out looking prudent rather than in trouble.
Especially because as they get bigger, their demand for 90th percentile types rather than 99.99th percentile types grows.
Plus, 15% would be a pretty small amount of deadwood at a company that size. It may just be specialists hired for departments that don't exist anymore or people that stopped caring 5 years ago, but have been around so long that they can't be fired.
...
when people deny any dead wood exists.