Prokhorkin didn't word it quite that strongly.
He said that he's always been a center and only played wing when circumstances like team composition and/or the directives of a coach dictated he had to do it, but he never enjoyed it. He's not one of those guys that can comfortably play every forward position and he thinks it would be really difficult to make the transition at this point in his career.
As a winger, he doesn't think he possesses the straight line speed to effectively skate in a lane (going from Point A to Point B) and gain separation from the defender to make himself available for a pass.
Playing as a center though allows him to see the entire sheet of ice in front of him to make a play, and because the position serves as a transition point between the forwards and defense, it allows him more touches with the puck.
Link (Russian)
Prokhorkin *did* say that he didn't want to play in the AHL and last off-season (before re-signing with CSKA) tried to get the Kings to guarantee that he wouldn't be re-assigned there and they flat out rejected that.
Link (English)
In yet another article (can't find the link right now) he said one of the reasons for staying in Russia was to physically mature against men at a high level of competition so that when he came to the States he'd be ready from the get-go to compete -- thus allowing him to bypass the AHL or needing to cut his teeth on the 4th line at the NHL-level.