Let's compare them for a bit...
Morris 5'9" / Zeke 6' / DMC 6'2"
• Morris had a couple years as a bellcow in 2012-2014 for the Redskins but his YPC has been in decline since 2013, and has been used as a change of pace back since arriving in Dallas last year.... presumably the role he was brought in for. He's never been much of a pass catching back.
• McFadden was the bellcow back when brought to Dallas in 2015, notching over 1000yds and a 4.6ypc in this offense. He's a capable reciever catching 40 receptions in this offense that same year... and having caught as many as 47 in his time with Oakland.
• Elliott is a fairly prototypical if not slightly tall back at 6', has been used as a bellow since arriving in dallas, averaging 5.1ypc last year, and is utilized moderately in the passing game with 32 receptions last year.
Literally the only thing in favor of Morris is that he's currently being used in his usual change-of-pace role, whereas DMC is a healthy scratch.
It comes down to if you believe that:
1) The Cowboys see DMC as a pass-catching / primary back type role, like the one he was brought to Dallas to do and is one year removed from doing successfully.... but who's waiting in the wings for news on Zeke.....
or
2) That DMC is a healthy scratch because he's not good enough to see the field, and Morris will suddenly take the lead back role, something he was not brought to Dallas to do, nor something he's ever done in Dallas, if Zeke is suspended...and DMC will be activated as backup.
Hopefully we won't find out.