After this week we'll see a lot from each guy.
Portis looks runs like his helmet is made of platinum, leaning forward and about to fall down as soon as he crosses the goal line. It's like how Cedric Benson ran in his final year with the Bears, he was lucky to gain more than 3 YPC. Torian will likely be the benificiary of Portis's awful play, but don't forget about Keiland, there is still a chance that the two of them will be battling.
Murphy has been great thus far, he even vindicated me last week when i started him over SmithNYG. But, as great as he looked, DHB is rising as another valid target in Oakland. Of course another option of the field won't hurt Murphy's value, but there is a chance that DHB may look more valuable on Monday morning.
In the end, it depends on your team needs, league scoring, and side of the bed you sleep on.