For years now, Microsoft watchers have wondered about the timing and other specifics of Steve Ballmer’s departure. Now we know them — or a lot more than we did yesterday, anyway. After 33 years at the company, the executive who started at Microsoft in 1980 and has been its CEO since 2000 has announced that he’ll retire within the next 12 months, once a successor has been named.

For folks interested primarily in the stock market, Ballmer’s time as Microsoft’s head honcho is defined by the fact that its shares have largely flat-lined during his tenure. Here, courtesy of Wolfram Alpha, is a chart comparing how MSFT has compared to AAPL during that time period:

If you — like me — don’t care much about Microsoft’s stock price, Ballmer’s legacy is far more complicated. It can’t be summed up in a chart or a tweet or even in one blog post.

I am not among the man’s harshest critics, in part because I believe that all tech-company hegemonies are destined to decline, sooner or later. The dustbin of tech-company history is littered with outfits which were once market-defining behemoths: Lotus, WordPerfect, Netscape, Palm and oh, so many more. Microsoft in 2013 is not a company on the verge of joining them: It’s still making vast amounts of money and managing to be highly competitive in everything from mundane business software to blockbuster videogames.