One of the most intriguing players on the Cowboys roster, defensive lineman David Irving, will rejoin the team today after serving his four-game suspension for PED use. Irving will make his 2017 debut this Sunday as the Cowboys host the Green Bay Packers in a critical Week 5 matchup, with the difference between 3-2 or 2-3 on the line.
Because suspended players don't count against your 53-man roster limit, Irving's return means the Cowboys will have to lose somebody to make room. There has been a lot of speculation about who will hit the discard pile. Here's my take.

The question of who should be released is an easy one for me. Backup quarterback Kellen Moore, who got outclassed during the preseason by rookie Cooper Rush, could probably be put on the street and remain a free agent. He also still has practice squad eligibility, meaning Dallas could keep him associated with the team to assist the other QBs and coaches in game preparation. I would pull that trigger without hesitation.
The fact that Moore is still here, though, suggests the team doesn't want to make that play. Therefore, we have to look elsewhere for our roster limit casualty. After being inactive for the first four weeks of 2017, running back Darren McFadden could make sense. Alfred Morris is the clear number-two RB now and Rod Smith brings too much on special teams. McFadden is the odd man out.
However, Ezekiel Elliott's ongoing legal status is why Dallas may not want to part with McFadden just yet. Until they have complete certainty that Elliott will play the entire season, the Cowboys will likely hang on to McFadden as he would probably find work if he hit the open market. Nothing in the NFL emulates fantasy football more than the RB position, where teams are scouring the waiver wire all year to deal with injuries.

Since David Irving is a defensive lineman, some might assume that's where the cut will come from. Second-year DE Charles Tapper has been targeted by some as he's been inactive the last few weeks. Irving is also able to play inside tackle, so Brian Price has also been discussed.
Right now the Cowboys only have nine defensive linemen, so adding Irving as a tenth would not create an unusual surplus. My gut feeling is that they don't want to lose any of their DL pieces this early in the year and with so much time for injuries to take a toll.
That same logic could be said about cornerback, where Dallas has six guys right now. Nolan Carroll and Chidobe Awuzie were out last week with injuries, allowing veteran Bene Benwikere to be active. Awuzie is expected back this week, though, to join Orlando Scandrick, Anthony Brown, and Jourdan Lewis at the top of the depth chart.
If the Cowboys are going to have those CBs active, and Carroll waiting in the wings, I think Benwikere is the easiest cut they can make. He doesn't do you any good in street clothes. If a future need arises at CB, Dallas might call up Marquez White from the practice squad or could potentially re-sign Benwikere from free agency.
There are plenty of options but these are the most likely routes that the Cowboys will take. We should find out pretty soon.