Pollard is a good example, a situational type of back. These type of players have had durability issues on the NFL level. He worked best as a #2 back with limited touches throughout a game. Gibbs is another example, he has Montgomery taking on most of the inside the tackle runs. Kamara had Ingram do the same. Pollard had Zeke.
Adams our new OC and former Cardinals OL Coach said he wants a physical run game. Look at his backs with Arizona: James Connor, Trey Benson. Big physical, power type of backs. Cowboys have always had that bell cow with a change of space type, Pollard, Randall, McFadden, etc. Remember, both Pollard and Randall were day 3 picks, I can see that happening more then taking Henderson first and then more of an every down workhorse type.