It's 'make phones or die'
Ballmer is getting pushed out because he took Microsoft's phone market share from 12% to 4±1%. According to Mr Orlowski, 'Windows Phone has been a success for Microsoft in 2013' but it has been a disaster for Nokia. WP took Nokia's market share from 35% to 4±1%. The only reason it got such a high market share was because the unsold piles phones were sold from the bargain bin at a huge loss. RT is about as successful as Windows Phone.
The desk top market is dying and the laptop market is not healthy. Microsoft are converting their desktop OS into a legacy business - the shinking market will be countered by increasing prices. At some point, the price will get so high that sales will fall to 0. Microsoft need a different market, and Bill has decided it is phones. The phone market is still growing. Phones are powerful enough to do common tasks that used to belong to desktops and laptops, and phones are getting more powerful each year.
Microsoft will continue to throw money at the WP/RT burning platforms for as long as they have money to burn. That is not poor management. It is sound business sense. The problem is that Microsoft have been utterly incapable of getting a significant market share. You can blame it on bad management, unenthusiastic salesmen, the developers, the carriers, or the dog that ate Ballmer's home work. What ever the reason, Mr Orlowski will be writing another article saying how well Microsoft have done to increase their phone market share to 2±1% next year.