Rooney's never going to be a midfielder. His first touch has never been great, but he made up for it by being able to chase anything that got away from him. His vision and passing are poor, with the extent of it basically being aimless, diagonal balls, hoping Valencia can get on the end of it. His shooting's gone too. He used to be a threat anywhere within about 25-30 yards of the goal, but he simply can't generate the appropriate power, or catch the ball as cleanly anymore, leading to embarrassing attempts like that one in the last game. If he doesn't have a lot of space and time, he struggles. He can't burst forward with the ball like he used to, so if we dropped him deeper to play in midfield, then what exactly is he going to do? He's not going to be passing it out and building from deep, nor is he going to burst forward with it and create opportunities that way.
The only way I can see Rooney adapting his game is by accepting that he's actually a striker, and sitting in between the two central defenders. We haven't got a use for someone who does that, but another team will, and playing regularly, I can see him bagging a fair few goals over the course of a season as the focal point of an attack.