Search is really really hard to do, isn't it? I mean there aren't that many search engines, and even more prominent "alternative" engines (like DuckDuckGo) are often pulling results from Google and/or Bing...both of which have made fairly gargantuan investments in the technology and infrastructure behind their search engines.
Could there be some other technical genius way of doing it? Well...I'm sure there is, but would Yahoo really have the in-house talent to discover it before Google or Bing (or another wealthy potential Search entrant like Apple or Facebook)?
Sure, Marissa has been buying up talent, but that has primarily been mobile devs...