Luck and Roethlisberger look similar in the pocket; both are big strong horses who aren't terribly concerned about a rushing DE who they most likely outweigh.  They know their physical size and strength can buy them a couple more beats of time if they see a route opening up down field.  Luck's wherewithal and confidence to pick up the fumble and dive it in separates him from about 80% of other QBs.  Could you imagine Brady trying something like that?  

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