What will be necessary is articulating a vision for the company which suddenly gets investors to sit up and say "this stock shouldn't be trading at these levels." Mayer has the ability to sell her vision and get Wall Street to buy in. She has the tech pedigree and the communication skills. So, what is left to hate? The financials? Well, we'll see later Tuesday when they announce earnings, but Yahoo!'s likely to show its second quarter in a row of revenue stabilization after four years of declines. The irrelevance of the brand? Well, 700 million people a month beg to differ and the fact that Mayer decided to leave Google to join Yahoo! willingly says that she believes it's worth going to and not fleeing. And, as a follow-on point relating to the board: why would she sign up to be presided over by a board that was still filled with bozos? Her hiring is an all-clear sign to investors on many fronts. There are still challenges facing Yahoo! and Mayer in this new role. She's never led an organization before, obviously, and we've never seen her perform on so public a stage as she's about to. Yet, if anyone had told you before Yahoo! hired Carol Bartz or Scott Thompson, that Yahoo! had a chance to hire Mayer, you would have said they were crazy. This is a big deal for Yahoo! and its investors. At the time of publication, the author was long YHOO.This article is commentary by an independent contributor, separate from TheStreet's regular news coverage.