Running backs come in all shapes and sizes, and the trend we see in the Class of 2017 is big and explosive. In fact, when looking at our ESPN Junior 300 there is only one back in the top 10 of our running back rankings under 195-pounds. Even the shorter, change-of-pace perimeter threats are well built with good physicality. As with all of our position comparisons this spring, this list is based off our current rankings, not the changes that are occurring daily as we approach the first release of the ESPN 300 in April. There could be changes, but they likely won't come at the top, where Alabama commit Najee Harris looks to become the first running back to be rated as the No. 1 overall player since Leonard Fournette in 2014.