IIRC it was normal for large companies (Sun, Intel, Oracle, etc) to terminate the "bottom n%" where n=5+ by some performance metric?
A lot of this is just managers that don't want to be confrontational and firing the guy who just isn't working out but seems perfectly happy to just keep sucking at his job. These 10% haircuts give them the excuse they need to do their job.
However, some well qualified engineers won't be bullied by such routines: they'll simply go work somewhere they're appreciated.
You could argue that they did it in the stupidest way though.