What you must be referring to is the stock price, which has dropped from 200 dollars a couple of years ago to like 120 these days.
I can't claim to understand this company, I think very few people can. There are 300,000 employees and more teams/products/departments than you can imagine. It's absolutely insane.
However, what I can say is the following: IBM is shifting it's strategy completely and that would've been very difficult to do without a drop in revenue and stock price. IBM is going from whatever it was before to a cloud-based company. All services and products will need to have some sort of cloud offering. I'm not sure if you can imagine what moving 300k employees worth of work to the cloud means. IBM has existed for like 100+ years now, this industry has not existed until a couple of years ago and, right now, all teams must re-evaluate their work and make the steps towards making this transition happen.
Many of the employees are stuck in their old ways, many people have been working at IBM their whole career (20-30-40 years) and it might be hard to adjust to so many new directives coming from the top. There's much bureaucracy and many old ways that need to be absolutely obliterated. Also, IBM doesn't have a great reputation for being cool or anything... almost everybody hates Lotus Notes, as an example.
This was sort of all over the place, I didn't spend a lot of time thinking about this. Please let me know if you have any specific questions...