I would normally say Slow Feathering gene too. I've raised English Orpingtons that took forever to feather in and looked really funny doing it. But I am a little concerned by the arrangement of feathers on yours. It already has all the wing feathers and some shoulder feathers, but a bare back... Some of the quills look a little odd. It could still be Slow Feathering, in which case everything will be fine... but I'd also watch to see that other chicks are not plucking it. As sometimes a less feathered chick can become a target.
I also found it helpful to feed a higher protein chick feed. Not a lot helpful, but enough to be worth trying. There's one I like by "Flock Party" brand (Manna Pro), they normally make treats, but this is a chick starter with 22% protein. They also really love the taste! Found at TSC. I'm not sure what other chain stores might carry for higher protein Starter.
Do they show signs of excessive itchiness? It can be hard to tell with chicks because their feathers coming in and changing out 5 times is really annoying for them so they groom a lot, but they can still get depluming lice just like adults can.
The one with feathers sticking out isn't frizzled, but looks like it has a feather quality issue. Sometimes it's just a little stage and then they look fine (remember, they get to change their coat 5 times before they're grown). Some of the others also have a ratty appearance, close to the feather shredding gene but probably not that. Really, my first instinct is to say "low protein"... are you giving them a lot of treats?