Destructuring a list containing two items to use it as arguments to a binary function

Here is one way to do what you ask

Through[{Mean@*List, Subtract}[1175., 247.]]
(* {711., 928.}*)

This works by using Composition (in its operator form) to apply List and then Mean to the inputs.

You could also "Lift" (is that the correct functional programming term?) Subtract to operate on lists (as suggested by @LukasLang)

Through[{Mean, Apply[Subtract]}[{1175., 247.}]]
(* {711., 928.}*)

One way is to force Mean to aggregate the two arguments into a list,

Through[{Mean[{##}] &, Subtract}[1175., 247.]]

Please notice the double ##. With only one # the mean will be applied only on the first argument.

Or you can modify the call to Subtract to force it to break the list into separate arguments:

Through[{Mean, Subtract[#[[1]], #[[2]]] &}[{1175., 247.}]]