I always play with my camera unlocked and still perform slightly poorly. Personally, its more of a psychological thing, seeing as attacking from "up" and having your attacks go "down" is a harder than shooting your skill shots "up". IMO, its not just me, seeing as many other games (like Space Invaders, Breakout, all the other arcade games etc) all have the "player controlled avatar" down. Playing League of Legends on Purple team is like trying to play Space Invaders with your spaceship on the top of the screen shooting downwards, not that difficult, but noticeable enough to make a difference.