ESPN did what they did because Google has declared April 21st D-Day for sites that are not built for mobile use. If your site is not fluid from desktop to mobile you stand to lose rankings. Having two site versions with device detection will not be an acceptable solution for them. Like everyone else with a site on the net, they need to have a one-web delivery set up.
http://searchengineland.com/everything-need-know-googles-new-stance-mobile-216870
http://searchengineland.com/everything-need-know-googles-new-stance-mobile-216870