If two guys are fighting for the football, I'm sorry, but the offense shouldn't be awarded a first down at the spot of contact. It's simply not fair. If an official feels as if contact was made by the defender, throw the flag. However, why not just make it a 15 yard penalty? Now, if a defender pulls an Ike Taylor and face-guards a receiver, pulls one or both of his arms down as he's trying to catch the football, or simply drags him down after being severely beaten on a long pass, then yes, penalize that man as many yards as are necessary.