Here's another one, the chair throw incident:
"At some point in the conversation Mr. Ballmer said: "Just tell me it's not Google." I told him it was Google. At that point, Mr. Ballmer picked up a chair and threw it across the room hitting a table in his office. Mr. Ballmer then said: "Fucking Eric Schmidt is a fucking pussy. I'm going to fucking bury that guy, I have done it before, and I will do it again. I'm going to fucking kill Google."" [1]
If you scroll up on there, you can read how very wrong he was on the iPhone, Linux, and FOSS.
Did he?
Microsoft kept Office relevant though, made Azure relevant, and are reinventing themselves from a proprietary to a data company (like Google, Facebook, and Amazon) who also do a lot of open source (like the previously mentioned companies). But I suppose Nadella takes credit for that.
Ballmer's failure as it related to Bing was trying to build an advertising platform to compete with Google and failing.
Financially, no.
Optically, yes.
(and, in fairness to the latter, in a manner which was diminishing longer term value creation also. However he totally does not deserve the reputation he generally has with developers. Like a lot of things, folks love to view them in black in white, when in reality it's a rainbow).