Why Dunbar was called up

The Cowboys run game has not lived up to their expectations through out the first 4 weeks. Last year, Demarco Murray got a chance and he showed the Cowboys he is the starter. He had the breakout performance against the Rams when he beat Emmit Smith single game rushing record for a Cowboy. He then went on to be productive a few more games but then had a season ending injury. Coming into this season he was expected to dominate again. The Cowboys thought that they had there long term running back set. And in week one he delivered, he had a plus 100 yard performance and an amazing run against the Giants. But after that he hasn't reached 100 yards again and only 1 touchdown. Now some fingers may be pointed to the offense line and how they have very bad blocks for Murray. Or how the Cowboys throw the ball more instead of running it. But either way, the Cowboys need to get some production back into the run game. With no consistency it forces Romo to throw the ball most of the time, and sometimes he doesn't make the right decision and turns the ball over. This is why the Cowbys signed Dunbar to the roster. The Cowboys are looking for a spark. Someone who can get yards and be consistent to get this offense going who ranks 29th in the run. Dunbar had a very impressive 100 plus yard performance in the final week of the preseason. The Cowboys though were happy with what they had so the signed him to the practice squad. But after 3 weeks in which the run game wasn't there the Cowboys knew they needed someone knew. I totally agree with this decision. One it motivates Murray, bringing Dunbar up is giving him a chance to take the starting job if he plays well enough. So Murray will try extra hard to prove he is the starter and will always be. Two Dunbar could be the answer to the run game. He could become a consistent runner who the Cowboys have been looking for since Emmit Smith left. But he could also be sleeper. Barely getting any yards and just sitting on the bench. My prediction of his performance is that he won't be a super star, but he will still do enough to spark the offense and show he is the number 2 running back.