If Dak Prescott didn't get hurt, Dallas would be at least a field goal favorite. Now they are home underdogs despite the Cardinals not playing that well and being on the road for a third straight game. 
The Cowboys, as it turned out, made a shrewd move signing Andy Dalton. He is a decent QB when surrounded with weapons. Dalton certainly has them here with arguably the best running back in the NFL, Ezekiel Elliott, and the top wide receiving trio in the league with Amari Cooper, Michael Gallup and CeeDee Lamb. They could torch a Cardinals secondary whose cornerbacks have been struggling. 
Dallas is without both of its starting offensive tackles. The Cardinals, though, suffered a major loss themselves when star pass rusher Chandler Jones was lost for the season. They don't have anyone who can rush the passer nearly as well as Jones. The Cardinals have received very little from heralded first-round draft pick Isaiah Simmons. He's been non-existent up to this point. Even with Jones, the Cardinals ranked in the bottom-five in pressuring the quarterback.  
I'm expecting the Cowboys to be super up for this Monday night home game wanting to show the nation they can win in their first full game without Prescott. Dalton will have had a full week of practice working with the first unit. He should be up for the challenge against a mediocre defense that just lost their best player. 
The Cardinals are 1-2 in their last three games. Their only win during this span was against the Jets. Their losses came to the Lions and Panthers. Arizona is 3-2 on the season. The three opponents they've defeated have a combined mark of 3-12.