That's a common misconception about Ballmer. The stock stagnated and they did miss mobile. However, if you look at their financials, under Ballmer revenue doubled and net income increased. Ballmer may not be the best person to identify and capitalize on new trends, but if you want someone who can make money, he's your man.

Because intelligence by itself does not assure success. I'm not a Balmer/Microsoft fan, but 'stagnated' isn't the word I'd use to describe Microsoft in Balmer's era: they missed mobile and got into search late, but they did extremely well in other areas.

COOs don't make good CEOs in general. They are great at executing someone else's vision, but not great at coming up with one on their own.

Ballmer focused on the unsexy enterprise market and missed mobile. He got beaten up for it in the stock market, but the company was still doing well