I look at it like this. Canales made his reputation as being responsible for the development of WRs and QBs prior to getting here. Supposedly that's why he was hired. After 2 season's the overwhelming evidence indicates that his reputation is in fact all bull. Those 2 positions have turned out to be the weakest links on the offense.
Now I understand he cannot make Young an nfl qb but he is in part responsible for the depth chart and in game decisions. But I do blame him for the lack of development and depth of the receivers.
Overall I think that Dan would be better suited cutting his buddy Dave lose and finding a better coach and let that guy find his qb. Or else he will go down with Dave.