Can't remember where I read it, but someone wrote about the first half-dozen games in the rookie seasons of several great running backs, and it looks like it took most of these RBs 4 or 5 games before they broke loose.  So my attitude is that Zeke should get another 3 games or so before concern/despair sets in.  
I thought he looked pretty good against the Redskins.  There were at least a few plays where he picked up more yardage than seemed to be available.  
I like this video -- good to see his runs all at once.  
http://www.dallascowboys.com/video/2016/09/18/every-ezekiel-elliott-carry-washington
He has some obvious ability.  He's quick and he can dart around.  If he can put it all together, he's going to be good.