1) Not accounting for declination in this area would have drawn them east not west. They went in the opposite direction at one point and them dropped down into the wrong side of the continental divide. The valley they found and the watershed they were then following was taking them south-west not east or south-east like they wanted to go.

2) "They were tired and dehydrated, but otherwise OK, Webb said." They may have been relying on a stove to boil water for them and simply run out of fuel. I was hiking for a week just south of there two weeks ago. Every stream and river were still running higher than normal, so there should have been plenty of water. There rescuers said they were dehydrated so some part of their water purification system was not working.