Obvious who I'm going with but here are some reasons. Carson is back healthy and has had all offseason to work with his young receivers. COC is the only WR who has not been around and is now there and will work with him in July, they have played together for a LONG time, this will be plenty to get their timing back. COC seems to have something to prove, that could be a good thing for Palmer. Despite losing TJ, this may be the deepest WR group he has had to work with. The line is the key to him, and while it is still shakey I think you'll see an improvement over last year. Andrews never impressed me aside from being very big, Collins stepping in there is an adequate replacement. If Andre Smith and Jon Luigs can step up as rookies you will see a big improvement. Not a great line, but adequate.
This offense has the weapons and Carson is still a great talent. To get this kind of combination of upside, weapons surrounding him, and talent in the 7th round is the kind of situations you dream about in drafts. I see no reason not to like his value where he's being drafted at right now.