There will be times to back the 49ers this season. This isn't one of them. Not with all the players the 49ers may not have. They could be the most banged-up team in the NFL right now. 
The Cardinals were undervalued by the oddsmaker last season when they went 9-5-2 ATS and they are at the start of this season with this large of a spread. 
Kyler Murray displayed great potential last year. He'll make a jump in this his second season surrounded by stronger weapons, including top-five wideout DeAndre Hopkins. Arizona also looks much improved defensively. 
If you discount a meaningless 49ers defensive touchdown on the final play of the game, the Cardinals lost to San Francisco by a combined seven points last season, an average loss of 3.5 points. The 49ers are weaker this season and the Cardinals are stronger. 
These teams are familiar with each other. It can't be overlooked either that division 'dogs have covered 81 percent on opening week since 2014, a sampling of 27 games.