ex-IBMer here. I rode this from 2001 until 2016 when it became clear that breaking up the company (as they recently did) would become the only sensible path forward.

While many poor decisions were made inside of the company, I ultimately blame Wall Street for IBM's downfall. Remember that back in 2011, Palmisano finished strong with IBM's Watson winning Jeopardy, IBM Software delivering consistent >80% profit margins on $10Bs in revenue, and a strong services backlog.

Many don't know that Palmisano's departure was preceded by a Wall Street mediated competition for the successor. IBM Software Group SVP, Steve Mills, was the obvious choice. The guy was a lifetime IBMer, intellectually superb, allegedly with photographic memory, effective public speaker, and with a proven history of leading (at the time) the 3rd largest software business in the world.

Unfortunately, Wall Street didn't like Mills because he did not come across well on CNBC. The guy is chubby and doesn't look like a conventional CEO. So Ginny Rometty, with a claim to fame based on building IBM Global Business Services from on the PwC acquistion became the leading candidate. Ginny is "media friendly" and the diversity factor didn't hurt.

Once Ginny came on board, leadership style changed from long-term to fickle and neurotic. Instead of committing to the hard work of building complex technology (e.g. cloud), any signs of technological challenges became reasons for business strategy changes at the top level. What started as a build decision (IBM SmartCloud) turned into a buy decision (Softlayer), followed by a build decision (IBM Bluemix), and so on.

However, Ginny's biggest failure was her inability to raise capital on Wall Street. IBM's engineers weren't failing at building cloud technology because the engineers were terrible (some were, normal distribution rules still apply) but because cost cutting policies starved engineering teams though attrition and lack of hiring. Staffing a team meant bringing in internal hires w/o the right skill set or taking a gamble on offshore (global) resource. At the same time Google was hiring left and right with comparative ease (as an aside, now they are dealing with the consequences).

Bottom line, Ginny couldn't get the capital to fund internal engineering efforts for the scale of the transformation needed to sustain IBM's success with machine learning (Watson) and cloud.

I place the blame on Wall Street since they made the bet on Ginny and then left her out to dry.