Ballmer is an idiot. Most specifically, he seems constantly to be in denial or ignorant about the reality of the competitive landscape, it's almost like he doesn't use technology or something. The reality is Apple is the HIGHEST volume player in tablets, the HIGHEST in MP3 players (there basically aren't any other players in MP3), they are the second highest in smartphones (next to Samsung), and the third or fourth (and one of the only players growing) in PCs. A case could be made that they aren't huge in PCs because even though they are the third or fourth largest PC maker in the world they only have around 10% of the market, fair. But when it comes to phones they definitely aren't low volume and continue to grow fairly quickly particularly in the US.
Back when the iPhone was being released Ballmer said he wasn't concerned about the iPhone because Windows Mobile phones already had those features, STUPID! Now he's busy talking with the same ignorant tone, like someone who doesn't use the devices, about how much he likes the Microsoft strategy in phones (where they are failing pretty badly) and tablets (where they might stand chance). The problem isn't even whether he's right or wrong, it just doesn't demonstrate a willingness to learn, a vigilance against the competition, they should throw him out.