Such a pretty rug, really. Great photos too. They show very clear what may be part of the culprit for the lower areas
Before reading this, i want to preface with saying of all the rugs you have here posted, this rug would be the most important to have someone inspect in person. If you opt for repair, you will want to get a firm estimate, and thorough explanation of proposed method and materials used. I don't think you necessarily stumbled into a jackpot, but it's not worth just beans either.
To answer your question about the wear, this is two probably two part.
1, use and age. typical wear pattern, unfortunately more heavy in some areas sthan other. But there's something else too.
2: Clear and undeniable heavy affect of dyes and or mordant in isolated areas: a high correlation between colors used and low areas. when you see this in a rug, it often indicates the weavers did not fully understand the long term affect of the dyes and/or mordant (used to make colors "fixed"). Wool subjected to this becomes "burned" with age, literally oxidizing and deteriorating making it more easily worn with use. Something used in creating the color of this wool was acidic. this is not uncommon to see lower piled areas of much older rugs although unlike this rug, most commonly these lower areas come from darker colors which were dyed repeatedly or used a corrosive metal to make the colors colorfast.
This rug should be properly fixed with formal restoration. Whether by you or a dealer or another individual. Formal restoration means
not removing or eliminating materials unless integral to revitalizing the carpet., or having someone recreate the pile in the same spirit the rug was originally made or "better". You want to have proper quality used with similar gauge, same spin, or even reintroduce antique wool with similar color natural dyes which have a proven track record. they sometimes pull old wool from antique worn flatweaves because the wool is continuous and already has the aged look.
As-is, and from what I can see, figure you could probably sell the rug for anywhere from $1,200 to maybe as high as $2000 or more. depends who is the buyer. Selling as is I think would be the smartest thing but you should make your own decision. I would get several opinions
I would imagine cost of proper repair (and the rug does deserve proper repair) would go
well into the 4 digits because there may be structural concerns which may be much larger than what we can see. Depending on who you take it to, they may advise more or less new knots be woven in. where you're located and what action may be taken, I would say a very good repair for all these areas would start at 3,000 or more. If it were my rug and wanted to repair, I would not have areas with knot heads showing re-woven, just the main damaged parts broken weft, and exposed foundation. You can see the copper wool has even affected other adjacent colors as well like the reds, no biggie to me, i'd rather keep the original knots
Auctions have been soft, so it is tough to say an [well] repaired final value, especially because originality would matter more for a rug like this that does not have heavy designer appeal. I would estimate providing excellent repair and all else equal, 8,000 - 12,000 at auction including buyer premium. Remember, auction houses will charge buyers AND seller premium, and taxes will need to be paid too... This auction value should be very carefully weighed with the time waiting for repair, change in markets, effort to find a good repairman for the job, upfront cost of having the rug repaired, etc.
If I were in your position, I would probably opt to sell the rug to a dealer or locally. For something like this dealers may even pay more because they often have more direct access to good trustworthy repairers. It's somewhat of cost prohibitive and time consuming proposal for individuals to pursue repair. I don't think this would be the best eBay rug, but its an easy way to get the rug out there. If you choose to go with ebay, i would set a fixed price with best offer for the first round. If you want I could ask to do a post on the main site for this rug to help get traffic.
As said before, unless you have fallen in love with the rug, repairing in your position is a lot of hassle, and you will not necessarily get the best result or money back if you choose to sell after. not to instill fear, but i have heard of cases where people pay for half of a repair up front, and a rug gets "lost".
On the other hand, if you find someone good, don't mind doing some investigation, and maybe want to learn more about rugs while doing so.... I think of all your rugs this one would have more sale potential. How much of a margin if any is up in the air, but worthy to sell as is for quick money.
Again, i would bring this to a local professional for full evaluation, but at least now you have some more information about what it is. A gorgeous example of a fereghan sarouk, natural dye, hand spun wool, approximately 100 years of age, and a little information about what it means to repair.