Cowboys' defense will be in state of flux

IRVING, Texas -- The chances of the Dallas Cowboys seeing their full first-team defense play together before the Sept. 7 regular-season opener against the San Francisco 49ers are slim, and that's not only because Orlando Scandrick will miss the first four games because of a suspension.

The third preseason game is the most regular-season game-like, and the Cowboys should get Brandon Carr on the field for the first time, but Morris Claiborne (shoulder), Henry Melton (groin) and Terrell McClain (ankle) are questionable at best. The Cowboys' starters have not played in a final preseason game since Bill Parcells was coach in 2006, although Jason Garrett said he anticipates Melton playing against the Denver Broncos if healthy. He should also want Claiborne, Terrell McClain and Rolando McClain to get action should the latter McClain become the first-team middle linebacker this week in practice.

The mixing and matching of the defense so far this summer has given more players chances to win jobs, but it has given the coaches less time to see which players work best as a unit.

The Dolphins' game will provide the best test for the defense just because of playing time.

"They are all tests. There is an opportunity every day, whether it's on the practice field or the preseason," Garrett said. "Your point is well-made though, that more of our guys are going to play and play together so we think that's a good thing. But every time you go out there it's a test. And hopefully you answer each and every day and you build and grow and get better and better. I thought our guys the other night who played did a good job. But it will be fun to see of those other guys who haven't been out there in a game setting go and play and see where they are as well, getting ready for San Francisco."

The Cowboys used nine of 11 starters from the preseason opener against the San Diego Chargers against the Baltimore Ravens last Saturday. Three of those starters were Tyrone Crawford, Davon Coleman and B.W. Webb. Coleman and Webb are not yet locks to make the final roster; Crawford took over at left defensive end for an injured George Selvie.

With Selvie getting healthier, Crawford might go back to a reserve role. Webb's case is helped by Scandrick's upcoming absence. Coleman will be pushed by the return of veteran Amobi Okoye to practice this week.

The Cowboys have been protective of their starters for fear of injury. Justin Durant has started both games at middle linebacker but played only 25 snaps. Slot corner Sterling Moore was held out against Baltimore because of a sore groin. Right defensive end Jeremy Mincey has played 26 snaps in two games.

Garrett was pleased with the incremental steps the defense made against the Ravens.

"I thought we simply made more stops than we did in the previous game against San Diego," Garrett said. "There were some good things. Obviously we've got to get better in a lot of different areas and we got to get some of these guys back to see them play but there's good competition for some of the starting spots and good competition down the line too."