Big, brash and bullish: how Ballmer's personality kept him at Microsoft's helm

He backed the Xbox division in the same way, although after the failure of Kin, the years it took to take Zune from a failure to a good product that still didn't sell, and the infamous Xbox 360 red ring of death, that looks like a little too much patience for far too long.

Troubled timing

"Microsoft's problem has never been spotting new ideas - it's been executing them. Often Microsoft has worked on an idea too early, not getting it right and abandoning it only to see another company make the same idea a huge success"

Rivalry, infighting and competing projects were problems he inherited but they remained too common under Ballmer. He never tackled the problem of how bad Microsoft has been at marketing even its successful products. Think about it: how many Microsoft adverts and marketing campaigns can you think of that haven't ended up making you cringe a little?

On the other hand, those issues are also what he put the company reorganisation in place to address. Unless the new CEO immediately reverses the reorg plans, Ballmer's decision to leave isn't the board (which includes Bill Gates, remember) doubting his vision. It's the board backing the reorg by wanting someone in place for the whole of the decade-long change it will take to make it stick.

They have to find someone who understands that they have to balance enterprise (which makes Microsoft the money today) and consumer (because all business technology has to include consumer technology these days, given how much of what we use at work gets brought in from home).

Ballmer spotted this convergence a few years ago, certainly before 2011 when the plan to run Windows on ARM devices was announced, and probably back in 2008 when he approved the plan to move Windows Phone onto the Windows kernel.

Microsoft's problem has never been spotting new ideas - it's been executing them. Often Microsoft has worked on an idea too early (it's been working on tablet devices and smart watches since the 1990s), not getting them right and abandoning the idea only to see another company make the same idea a huge success.

But what Microsoft also famously does is get things right third time. Let's hope that's true of its third CEO.

• Ballmer's not the only successor to a founding tech visionary to face pressures: read why Kate Solomon thinks Apple's Tim Cook should resist the rush to innovate.