The running backs are the exact reason an examination of positional ADP tiers is necessary this year. They are swimming in dead zones, and those puppies can be ugly.

David Johnson and Todd Gurley are the only two running backs with an ADP inside the top six picks right now, essentially making themselves into their own tier. Then we get a second grouping of four running backs within 4.4 picks, formulating a nice, tidy second tier.

That's when things get a little weird.

The two dots that form the bridge between the second and third tiers are Jamaal Charles (ADP of 17.9) and Devonta Freeman (19.5). This is a bit different from what we saw with the quarterbacks, though. Charles has the potential to be the top back in fantasy, and Freeman was exactly that last year. You could make an argument that their value is closer to that of the second tier than that of the third, making their awkward ADPs a bit easier to swallow.

The same cannot be said for Doug Martin. He is currently the most middle-of-nowhere little bugger in the entire draft. There is a cushion of five picks before him and five picks behind him in which no other running backs are selected. There's a fairly meaty tier right behind him with six running backs separated by nine picks, making his value fairly replaceable. It looks like a situation where if you don't get one of the top 11 running backs, you're best waiting until the fourth round to dive into the position.

Our search for the optimal drafting tier at running back may hit at roughly the sixth round. There, we have our 25th-ranked running back (Giovani Bernard) through the 30th-ranked running back (Melvin Gordon) all in the span of 10 picks. There's plenty of upside in this tier, and even if you miss out on some assets, getting Gordon as the lowest-hanging fruit gives you flexibility.

A second wave of running backs at pick 80 through pick 90 -- when paired with the aforementioned tier in the sixth round -- is what could allow you to go hard at wide receiver early in your drafts. There are dead zones earlier for running backs, but there are plenty of valuable options in the sixth, seventh, and eighth rounds from which to choose. These are the types of tiers around which you can formulate your entire plan of attack, and you will want to be picking running backs in this range, especially once you see how quickly things turn south at wide receiver.