Well, they let go of a lot of people with actual skills and knowledge because they made too much money. People with the know-how (my Dad being one of them) saw the writing on the wall decades ago and hit the door even before being pushed out due to age.
They're absolutely embarrassing now. They've lost too many good people and everybody knows what IBM's about now. They can focus on hiring Millenials all they want, but which early-stage workers would really want to go to IBM? They know what it'll be like. Lots of outsourcing, bureaucracy and bad decisions. Not many would choose IBM over another offer.
Screwing over the workforce has consequences.