NEW YORK ( TheStreet) -- We've heard the term "So much to do, so little time." But this would seem the opposite of all of the things that Yahoo! ( YHOO) has been able to accomplish in a span of just 12 months.I'm not going to pretend that Yahoo!! has "arrived" to where CEO Marissa Mayer envisioned the company would be. After all, there are still real threats from Google ( GOOG) and Facebook ( FB) that the company is working to mitigate. What is clear, though, is that Yahoo! is no longer the pushover that it once was. Here too, Mayer has had a huge in changing the company's image. And with a few more improvements in some key areas, these shares still look undervalued on a long-term basis. Yahoo! continues to be one of the most misunderstood companies on Wall Street. Investors still want to remember the company as a search pioneer. Heck, even Yahoo! has been searching for its own identity. But the "search" is over -- at least in the philosophical sense. And Marissa Mayer is a good reason for this as well. Mayer has brought a winning attitude that Yahoo! has not seen for more than a decade. Since her arrival almost a year ago, Mayer has been working to transform Yahoo! from just a media site to a true technology company. Whether through internal operations or acquisitions like Summly and Tumblr, Yahoo! is quickly building its capabilities by leveraging its assets to offer high-quality services to the consumer markets and mobile devices. While Yahoo! still has a dominant media presence in finance and sports, Mayer is also building Yahoo!'s position in social and apps. How well these acquisitions will work remains to be seen. However, the company is also acquiring a considerable amount of engineering talent in the process -- the type of talent that will help Yahoo! to capitalize on future market opportunities -- the type of opportunities that it missed and allowed Facebook and Twitter to seize. Some will disagree. But Yahoo! does not fear either Facebook or Twitter, or any other competing platform. Given the fact that Yahoo! still brings hundreds of millions of unique visitors every month to its email, sports and business franchises, it would be foolish to bet against Yahoo!'s ability to monetize this type of traffic going forward. Let's not discount that Yahoo! faces strong competition in these areas from the likes of Disney ( DIS), which owns the rights to ESPN.com.