Tough to say really.
Last season...despite the historically bad defense, very similar staff, injuries, etc...they still had a chance to win the division, went 5-1 in the division, & the offense was the 5th highest scoring in the league. Add to that, they lost 5 games by a combined 8 points (three 1 point losses, one 2 point loss, and one 3 point loss).
Despite injuring his back in the game vs. the Skins...Romo still scrambled well enough to avoid pressure & toss the game-winning TD. They have a pro bowl RB, a HOF worthy TE, one of the top WR's in the league, a solid #2, a sneaky slot option, and an O-Line that could wind up being among the better in the league. I think the offense has a chance to be in the top 5-7 in scoring again minus injuries.
As far as the defense, they aren't going to be very good. That said, even minor improvement in a couple of areas like 3rd down efficiency & turnovers would help. Forcing a single key punt (which they didn't do in 2 1/2 games last season), could help win them a game. Will also be curious to see how things shape up when guys like Spencer, Lawrence, McClain, etc. return. A guy like Brent could help improve the run defense if/when he's added. They can use all of the help they can get.