FORTUNE — Since becoming Yahoo’s CEO almost two years ago, Marissa Mayer has promoted her theme of “digital daily habits.” Yahoo’s turnaround would include a major push into mobile, re-engaging with the company’s large audience on a daily basis through its large portfolio of apps.
Mayer’s strategy for this includes buying 36 mobile startups and Tumblr. It includes relaunching Flickr, the photo-sharing site, and giving away a terabyte of data to each user. It includes launching new mail, weather, news apps.
Some of the apps have been well-received by reviewers. But none have become top ten apps. According to App Annie’s rankings of app downloads, only Yahoo Mail has made a dent, landing at #43 for iOS and #20 for Android. (Meanwhile, a game created in a few weeks by a 16-year-old in Florida called 4 Snaps has skyrocketed into the top spot for iOS apps in the Word category, the top 50 for Games, and top 200 overall, in a matter of weeks.)
Fortune‘s latest cover story asks whether Mayer can save Yahoo. This year, for the first time in nine years, Yahoo (YHOO) will not be a part of the Fortune 500.
MORE: Marissa’s moment of truth
On stage at the TechCrunch Disrupt conference today, Mayer admitted to Yahoo’s struggles with mobile. “Last year was the year we began to make investment in mobile,” she said.
“We’re late. We’re behind,” she said, adding that Yahoo has “made great strides” since she joined the company. She is proud of changes to Yahoo’s mail app, its weather app, and Tumblr’s mobile app over the last year. Engagement has picked up, she said. Yahoo is working on a new games platform and is continually improving its communications tools, which are the two most-engaging ways people use mobile phones.
Getting mobile right is “a really critical issue, and a missed opportunity,” Mayer said. When she arrived, very few people were working on mobile products at Yahoo; now Yahoo has hundreds of mobile developers. By the end of this year, Yahoo’s mobile users (currently 430 million monthly) will overtake its desktop users, Mayer said.
It was a rare admission of shortcomings in an otherwise politic interview. At one point her interviewer, Michael Arrington, became frustrated with Mayer’s perfectly on-message answers. “I cannot throw you off,” he said. “It’s annoying to me that I can’t.”
Mayer was careful not to reveal anything about the biggest topic of speculation around Yahoo: Alibaba. When the Chinese Internet giant goes public later this year, Yahoo is expected to reap a windfall of $10 billion. What will it do with the proceeds? According to Mayer, Yahoo will be a “good steward of capital.”
“That sounds like it was written by a lawyer,” Arrington said.