Most of the talking heads don't really think AP will make a difference because of the offensive line in Arizona being, well, bad. Really bad.
While I don't think he's a David Johnson type talent at this point in his career, I do think he is leaps and bounds above Chris Johnson.
The key is whether Arizona will use AP like they need to. He's a bruiser and needs 15-20 carries to do what he does. This could be really good for the offense to keep Palmer from having to throw the ball 40-50 times a game.
This was a good move by Arizona! It may not show in week 6 or even 7, but give him a few weeks to learn the offense and he'll be ready for action!