Actually Ballmer did many things correctly. There was an incorrect call / arrogance in approaching the mobile phone market a certain way, and delay in building

Actually Ballmer did many things correctly. There was an incorrect call / arrogance in approaching the mobile phone market a certain way, and delay in building something like their hardware organization. But I don't think this means Ballmer was a complete failure. Microsoft delivered stellar results in many dimensions during Ballmer's years as well.