Right?!? Does it even really matter. Last time I checked they both missed the playoffs. But for arguments sake the cowboys have a top 5 WR, Top 5 Te , 91 rated QB, and probably one of the higher rated offensive lines this year. The cardinals have a top WR. I'm pretty sure the Cowboys offense helped give that rating of 81. Also, the ratings are not based on what the teams did last year...they are projected with free agent signing and draft picks.
I think the Cowboys ranked 15 amongst the NFL teams right now is about right. That is were they have been the last few years as a franchise.