Having that runner/pass catcher role filled really makes this offense shine. NFL teams rely on those players to generate easy 3rd downs, like Ty Montgomery mentioned above, Alvin Kamara, Darren Sproles, our own Duke Johnson, and so many others. Having an extra player on the field that can find the sticks is awesome. Pick up the blitz with a chip block, then slip out to the flat for an easy 6 yards. When it works it feels like cheating.