So if you have two kids that are both talented and are good lax players you would bring up the kid thats not a middie and play the kid at middie as oppose to bringing up the true middie thats also talented. Don't get crazy just using those positions as an example. So a team should draft a line backer and make him a running back or draft a running back. It's interesting to see how people respond to the question.
Enough with this. There are no set positions - you are either an offensive player or defensive player and that means you can be moved around. If you are an inflexible player intent on just playing one position and either only righty or lefty, bring some cushioning for the bench.