Ross, the whole mindset is different. At RB attacking is a useful extra, at RW it's the whole point. Far more often than not RW gets the ball from behind him rather than being able to run on to it. These sorts of switches rarely, if ever, work for just those reasons.
Besides, Magic's defensive play isn't THAT bad. The idea that it is is a myth peddled by the media and it continually amazes me that so many Reds fall for it.