What is all of the wearing off of the edges from? This was a 1981 build with a 13 yr old roof.
If it was up here in the Pacific NW, I would say it was from pressure washing the moss off. It builds up along the edges and in the keyways so that is where they aim the nozzle. Not sure how much moss you guys get down there.
If this is true, the original roof was replaced when it was only 14 years old. Those types of shingles (3-tab) can wear out pretty quickly.
How well was the attic ventilated?
I think I would tell my client since I wasn’t there when the tabs became damaged anything I told you would be a wild guess, besides the fact that you need to budget for new shingles…
And from looking at the photos, I would recommend tearing those off before installing another layer, even if this is the only layer on the roof, either the felt paper was not installed flat, or there are a two layers on there now by looking at the uneveness in the pictures.
Regardless, it looks like the mineral covering is about shot and the shingles look brittle in the pictures…but thats just a guess from Arizona…
Some of those images appear to show hail damage
Regards
Gerry
Poor installation, weather, age…just to name a few…anything in my part of TX is required to have hail evidence within the 5 year mark and especially in the stated amount of time or it’s not a real shingle 
Manufactures say 15-20-25-30…I say they’re done when they’re done. They are doing complete tear offs and replacements of 30-50 yr products that were installed last year.
Why didn’t they last any longer? Weather!
Just in case you slept through class, weather, hail and wind will F-up a roof! 
ventilation was decent. i’ve seen and felt worse (152, per infrared) on the last bad one.
i told the agent it’s time for a new one.
thanks for the input.
You live in TX!
You answered your own question.
Richard, you mention it was well ventilated but based on the photos, I did not see a ridge vent. It also looked like a hip roof which limits the amount of ridge vent you can install. IMHO
I didn’t see any bruises from hail, but I did see horizontal cracking, which indicates a cheap light weight shingle with too much sealant adhesion, not allowing for expansion and contraction, hence the buckling and wavy look to the entire roof surface, unless this is already a multi-layer roof application, which it does not look like. I did not see any signs of any underlying shingles telegraphing through the shingle surface.
Ed
Good eye Ed
Looking at the pics, the keys are showing evidence of being pulled back by strong winds. observe the ripping in a lot of them.