OK,I decided to punch the numbers so you seem mostly correct now.
In fact at 4K the GTX1080 can sometimes edge out the GTX980TI - The Division and the AOTS by a decent amount.
Although in FarCry

rimeval and BF4 it is the other way around.
Game 1 - Fallout 4
1080P overclocked,GTX1080 is 14% faster than an overclocked GTX980TI.
4k overclocked,GTX1080 is 15% faster than an overclocked GTX980TI
GTAV
1080P overclocked,GTX1080 is 15% faster than an overclocked GTX980TI.
4k overclocked,GTX1080 is 14 % faster than an overclocked GTX980TI
Shadow of Mordor
1080P overclocked,GTX1080 is 25% faster than an overclocked GTX980TI.
4k overclocked,GTX1080 is 21% faster than an overclocked GTX980TI
Far Cry Primal
1080P overclocked,GTX1080 is 26% faster than an overclocked GTX980TI.
4k overclocked,GTX1080 is 18% faster than an overclocked GTX980TI
Battlefield 4
1080P overclocked,GTX1080 is 30% faster than an overclocked GTX980TI.
4k overclocked,GTX1080 is 26% faster than an overclocked GTX980TI
The Witcher 3: Wild Hunt
1080P overclocked,GTX1080 is 21% faster than an overclocked GTX980TI.
4k overclocked,GTX1080 is 24% faster than an overclocked GTX980TI
Hitman (2016)
1080P overclocked,GTX1080 is 29% faster than an overclocked GTX980TI.
4k overclocked,GTX1080 is 28% faster than an overclocked GTX980TI
Tom Clancy's The Division
1080P overclocked,GTX1080 is 11% faster than an overclocked GTX980TI.
4k overclocked,GTX1080 is 20% faster than an overclocked GTX980TI
Ashes of the Singularity
1080P overclocked,GTX1080 is 27% faster than an overclocked GTX980TI.
4k overclocked,GTX1080 is 32% faster than an overclocked GTX980TI
So an average of 9 games,an overclocked GTX1080 is 22% faster at 1080P than an overclocked GTX980TI.
So an average of 9 games,an overclocked GTX1080 is 22% faster at 1080P than an overclocked GTX980TI.
Not much in it - teaches me to skim benchmarks!!