Let me try to sort out the confusion here in Dallas' coverage schemes.
First of all, Newman will be manned up with Jackson for the majority of this game. Jenkins will line up with Maclin.
There are occasions that Wade likes to simply assign Newman to line up with the opponents #1 WR no matter which side they line up, as he has done with similar receivers in Carolina's Steve Smith and Redskins receiver Santana Moss with great success. I expect to see it again this week with Jackson.
As Bankerguy pointed out, Sensabaugh and Carpenter will share assignments to Celek. Expect him to be neutralized just as Carlson and Gonzalez were the last two weeks.
Rolled safety coverage will depend on the Eagles personnel on the field and the defensive play call.
In most cases, when there is a slot receiver in a three receiver set, the outside corner on the slot side will hand off deep coverage to the safety at the break of the slot receiver and undercut the slot receiver's pattern. This is where their interceptions have developed lately. If the ball is thrown deep to that side to the outside receiver, the safety has already rolled over the top while the slot corner has already dropped to cover the underneath once the outside corner has established position on his slot receiver.
This is something that has taken some time for the secondary to master, but they've been getting better and better with it from week to week and it has been producing results. It's difficult for the quarterback to read and determine the open receiver, especially with the pressure that the Cowboys have been bringing.
NFL Live demonstrated this quite well last night.