The F-15Cs that we have are wearing out.
“The F-15Cs that we have are wearing out.”
I think that is the right answer.
In order to preserve the Air Superiority mix of “high/low” with the F-22s, we need more “low” F-15s. The ones we have are worn out, and their avionics/weapons are aged as well.
Hopefully they will do a better job than several of their recent efforts.