While many posters were knocking Oweh's performance last year and questioning his ability to contribute in the NFL based on his production, analysts were praising his on-field performance and citing it as evidence that he was more than just a great athlete. IIRC, the argument was that as Oweh's presence and performance opened things up for the rest of the defense, and one could see it in the team statistics when comparing when he was on and off the field.
As for Parsons, he seems to excel in whatever role Dallas gives him. One of the talking heads was talking about his sack ratio for the number of times he rushes the passer - he's in a class by himself. At the same time, because he can do so many other things exceptionally well and Dallas uses him in multiple roles, it's all but impossible to scheme against him. Making him an edge rusher most of the time would take that away.