Yahoo! CEO Marissa Mayer's First Flub

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NEW YORK ( TheStreet) -- Marissa Mayer was named Yahoo! (YHOO) CEO July 16, and since then has enjoyed a cozy relationship with the media and Wall Street, as she tries to turn around the struggling Internet giant. The gloves came off yesterday, though, as one of Yahoo!'s top properties, its fantasy football site, was down on a crucial day.

As Mayer looks to turn Yahoo! around and compete with the likes of Google (GOOG) (her former employer), Facebook (FB) , and other companies supported by advertising revenue, Mayer's increasingly looking to focus on mobile, and the company's apps, which are lacking. Yahoo! even made its first acquisition under Mayer recently, grabbing the iPhone app Stamped.

On the conference call discussing third-quarter earnings , Mayer noted that Yahoo! has not done a great job with its mobile efforts. "And while we've made progress, Yahoo! hasn't capitalized on the mobile opportunity. We haven't effectively optimized our Web sites, we've underinvested in our mobile front-end development and we've splintered our brands," she said. "We have more than 76 applications across Android and iOS. All of this needs to change. Our top priority is a focused, coherent, mobile strategy. We're accelerating our efforts to build a strong technical talent base for mobile. This includes engineers, product managers and designers."

If focusing on mobile apps and building a better experience for your users involves one of your most important properties suffering a severe outage, then a significant amount of work needs to be done. It's certainly not a great way to start.

The fantasy football property first went down around 12 p.m. EST on Sunday, and was down most of the day, according to several users. This is more than just an annoyance to fantasy sports players such as myself, as fantasy sports has become big business. Not only for the players themselves in terms of prize money, but for Yahoo! too, which gets significant amounts of traffic.

Mayer's Twitter account was flooded with angry users who could not access the app. Here are just a few of the mentions she received, including one from myself:

.@marissamayer I understand you'll be focusing on mobile. Hire developers who make your mobile apps work. Fantasy Football not working $yhoo— Chris Ciaccia (@Commodity_Bull) November 11, 2012

@marissamayer The only thing that makes Yahoo relevant these days is fantasy football and you super failed today. Gonna be hard to rebound.— Matt Notley (@notmattley) November 11, 2012

@marissamayer this will be the last year I use your service for Fantasy Football. I'm beyond disappointed.— Mike Berry (@mikehberry) November 11, 2012

Sunnyvale, Calif.-based Yahoo! sent out an email very late last night, apologizing to users, trying to stem the issue, but that won't help the millions of users that lost access, and subsequently lost their match-ups because Yahoo!'s servers went down.