Yahoo! announced tonight that Google's Marissa Mayer would take over tomorrow as Yahoo!'s CEO and President.  Obviously Mayer has long experience in the space and brings good competitive knowledge, particularly related to search marketing.  But I'm disappointed by this choice, here's why.

*Yahoo! needs a strategic visionary, not a product engineer.  Yahoo!'s fundamental problem is that it has too many disparate products with no clear unifying thread that ties them all together. And Mayer's background is in product development…not corporate strategy, not marketing, not brand definition…the areas where Yahoo! has the most critical need.

Yahoo! needs a strategic vision, not individual product promotion.  My other worry with Mayer's appointment is that it signals yet another shift in strategic vision for Yahoo!.  I count four different strategies over the last four years.  Late Jerry-Yang era Yahoo! was all about building Yahoo! as a provider of ad management technology and a portable social ID for consumers.   Bartz era Yahoo! refocused the company on being "the best media company in the world," by developing content creation resources and proprietary online magazines.  Then, Scott Thompson re-introduced Yahoo! shopping and Yahoo! as a commerce technology provider.  Now, Yahoo! seems to be chasing a new vision: one which emphasizes individual Yahoo! products, over a big-picture brand. I am not a fan of this vision (see my first point above), but I also hate that Yahoo! can't identify and stick with a clear strategy for more than about 10 months.

The optimist in me hopes that the third time will be the charm here for Y! with its post-Yang CEO choices.  Mayer will prove me wrong if she can:

1) Define a clear vision for the Yahoo! brand;

2) Get rid of the extraneous Yahoo! products that have nothing to do with that vision (say its Web hosting or domain registration businesses?); and

3) Market the new vision clearly so that business and consumer customers know what Yahoo! is and why to use it.