With Richard Ash called up to help run D, where do Cowboys get game-day spot?

Bruschi, Edwards like Cowboys over Niners (0:39)

Tedy Bruschi and Herm Edwards side with the Cowboys because of the 49ers' weak defense. (0:39)

SANTA CLARA, Calif. -- Sometimes in looking at a game-day roster it can simply be a process of elimination.

That’s the way coaches would like it, using the same 46 players each week and never having to worry about too few defensive backs or too many offensive linemen.

In attempting to decipher the Dallas Cowboys' 46-man roster for Sunday’s game against the San Francisco 49ers, some decisions would appear easy: Cooper Rush and Darren McFadden have been inactive for the first five games. New linebacker Justin March-Lillard isn’t really ready. Cornerback Chidobe Awuzie is working through a hamstring strain. The Cowboys don’t need six receivers, so Noah Brown could sit again, but a case can be made for him as a special-teams player.

So, where do the final two inactive spots come from?

The Cowboys called up Richard Ash from the practice squad Saturday because they wanted some interior depth on their defensive line. If they weren’t going to play Ash, why make the roster move other than in case somebody gets sick the night before the game? OK, that might be a good reason to make the roster move -- you have to be prepared for emergencies. But if Ash is active, then you have to wonder whether Taco Charlton or potentially Benson Mayowa would be inactive.

But on Friday, linebacker Justin Durant was added to the injury report with a groin injury and is listed as questionable. Durant’s injury history tells you he might miss a game or two. Perhaps if he is out, March-Lillard will be needed.

In their past two games, the Cowboys have dressed eight offensive linemen, which really isn’t necessary. Chaz Green and Byron Bell did not play an offensive snap in the losses to the Los Angeles Rams and Green Bay Packers. One of them has to dress as the backup swing tackle, but the Cowboys don’t need both of them active.

But let’s say the Cowboys want to have an eighth offensive lineman or a sixth receiver active. Where does the next roster spot come from? It could be Durant.

So, the guess at Sunday's inactives is: Rush, McFadden, March-Lillard, Awuzie, Ash, Green and Durant.