The real problem was Microsoft under ballmer completely utterly missed the biggest computing revolution of the last 20 years.
Mobile.
That put Microsoft so far behind everyone in the industry that it forced the board to remove him...
He actually did a GREAT job in the enterprise space and efficiently maximizing profit in the other old school Microsoft sectors...
Put it another way... When Ballmer took over Microsoft owned +70% of computing OS market, when he left they owned something like 30% and were stuck on a trajectory where today they are at like 15%... Microsoft was primarily an OS company... He more or less sunk the company