* Some of the big feathers in Microsoft's cap today (O365 and Azure) started during Ballmer's tenure
* While the company had plenty of failed initiatives during his time, what matters in the end is that the hits made up for the misses in terms of profit, and they did
* Metrics like revenue and so on were all positive during his tenure
Frankly, unless the author is factually incorrect on these points (which I don't have the knowledge to assert either way), I think it's a good argument.