I think most people, while they wisely grasp the strength and athleticism of the defensive players, are underestimating the talent of NFL offensive lines.
Most plays, the deep back waits a moment while the QB takes the snap, and the blocks start to develop, then uses his strength, speed, athletic ability, knowledge of the playbook, and understanding of what it means to read the play on the fly to explode forth and average...oh, four yards per carry or so.
Most plays, however, there are going to be more defensive players committed to stopping the pass than the run. Meaning that the offensive line typically gets a bit of a push, and by the time the RB gets there, even if he runs head on into the first defender, it's rarely for a loss.
Optimal strategy for we less gifted types would be to just go for the hole the play was designed for and hope for the best. I assume most people here, with a bit of time invested, could at a minimum come to understand the playbook that deeply. When it comes to ability to study a little information, I don't think Demarco Murray is all that much better off than I am. His advantages lie in every other possible metric.
Anyway, assuming a typical offensive line push, plus a significant delay in how long it would take me to get to the designed hole relative to Demarco (probably a full half second later or so?), the D has now had a chance to read and react and would probably push back a bit by the time I got there. Still, unless they called the perfect run blitz to counteract the threat of a Freelove run (which seems unlikely, since why would they bother when I'd clearly be the least threatening offensive weapon on the field?), I'd probably almost be able to reach original line of scrimmage around the time the defense started pouring through.
I think those saying -7 yards are being pessimistic or are just giving the magnificent athletes on their own front lines too little credit.
I think a loss of about a yard, coupled with (of course) an instant career-ending injury would have my average much closer to zero than some of you seem to think.
Unless I panic and fall fetally to the ground before the play even begins to develop, which is a distinct possibility.