They all look normal except the frizzle. Feathers grow in tracts, with completely bald areas between the tracts of feathers. Pick up a fully feathered bird and separate the feathers and you will see maybe half, a third of the bird has bare skin. That's normal. They also molt and grow the feathers in that tract as a group. The back feathers seem to me to be the last to feather out in chicks.
Your frizzle looks like it has a double copy of the gene for frizzling. I hope I'm wrong. The frizzle gene is an incompletely dominant gene. One copy of the gene paired with a normal feathering gene makes that beautiful frizzle with a wide feather curling away from the body. Two copies of the gene produce a "frazzle" or "curlie" which has a thin, weak, brittle feathers very susceptible to mechanical damage. Often all that will be left of the feather is the hard wiry shaft. Their feathers will look dull, oily and matted. If you handle them, feather parts will break off. They have a lot of trouble surviving because they have very little protection from the cold.
Frizzle birds should never be bred to frizzle birds unless whoever is doing the breeding is prepared to deal with the resulting 25% frazzle birds. Serious breeders will do it and cull the frazzles. I know hatcheries are doing it because their catalogs advertise that their chicks will be 75% frizzled and 25% will be smooth. The only way to get that ratio of frizzles is to be breeding frizzle to frizzle.
A proper frizzle breeding will have one normal frizzle parent (genetically Ff, with "F" being the gene for frizzle and "f" being the gene for smooth, normal feathering) and a smooth (ff with two copies of the smooth feathering gene "f"). With that breeding half will be frizzle (Ff) and the other half will be smooth (ff). If you breed frizzle (Ff) to frizzle (Ff) you get 25% smooth (ff), 50% frizzle (Ff) and 25% frazzle (FF). If someone doesn't understand how I got these ratios, I will be happy to try to explain.
I have two hatchery frazzles. They spent the winter in my house, the most naked one in my kitchen where she laid an egg almost every day. I had her out with a flock of only pullets when one day my Silkie and (frazzled) Cochin cockerels escaped from their bachelor pen. Everyone was so happy, I left them all together. I put an apron on the frazzled pullet and thought that would be enough protection for her. I was wrong. Between the cockerels grabbing the back of her neck and the apron wearing off her feathers, she ended up basically naked. She is just starting to molt her broken feathers. She is kept in the house at night and in the day is out with my Ameraucana chicks in the parrot aviary. Here are some pictures of her:
Before the cockerels and the protective apron broke all her feathers off:
I will breed (artificial insemination) this frazzled pullet to my show quality smooth feathered Cochin and get 100% frizzled birds. It has been a struggle and quite an inconvenience to keep my two frazzled birds alive this winter.
I hope I am wrong about your frizzle. Can you send some better pictures? The dull, oily looking feathers are what is worrying me the most. Chicks, frizzles included, should have healthy, bright shiny feathers. Frazzles don't. Do the feathers seem to break easily? If you pick the chick up and look at it's feathers, do you have bits of broken feathers on your lap? I really hope I'm wrong.
I was hoping you would see the pictures I posted.

I do like the idea of breeding a smooth feathered with the frazzled and getting frizzles but I'm not sure if that's something I'm going to get into...but it sounds fun...hmmmm...I really don't need to...but I want to...

On the other chicks with slow back feathering, have you found the 'theory' that they are cockerels to be true for you? I have 3 standard cochins in the mix, different colors, that I'm wanting to hang onto but they seem to have naked backs. I was hoping its a breed trait and due to their large size but if more than likely they're going to be cockerels, I need to save myself from getting to attached...We plan on processing most of our males this year ourselves but right now, while they are all so friendly its going to be hard. I agree with your theory that I know we are giving them a good life, feeding them well, and we should be the ones to benefit from them, not someone else but its hard not to have 'favorites'. Of course, once hormones kick in, they might not be so cute!