That sounds crazy to me, but yet it seems like what a lot of people are saying.
It's less crazy than you think. People could be concerned he doesn't hold up and either gets hurt or is rendered ineffective, costing you those crucial end-of-year and playoff games. Another thing not mentioned is his expected touchdown regression. He's not the goal line back and is ineffective when used as such. He's bound to cede carries within the five to one of the other Dallas backs. He scored 12 touchdowns last year over an expected 7-8 touchdowns, per PFF. He's actually due for a regression in that sense.
Those are the good arguments against Pollard. Like I said in this thread, I personally took him as RB7 (the 2.03 in one draft) this year. Everybody's mileage gonna vary on this one, but the above argument makes sense if you're worried about durability and availability.