I'am currently playing a PBEM game in May 1915.
You are in october 1915.
Looking at your screen, i see around 11000 Allied CP in a very short front (without belgium). The ennemy (is it the AI ? Did he have economic bonus due to increase difficulty ?) seems to have concentrated a big part of its troops in one point for a massive offensive.
I did not see your 5*4000 CP troops (which would be 20000 Cp total, which would be far more strange).
In my PBEM may 1915, i see around 8000 to 9000 ennemy western combat points on western front, not counting the reserve he probably have hidden from my sight.
So it is a big army but not impossible.
Did you sent too much troops against russian ? you can align 10K cp combat power easily too on western front
I notice that your manpower reserve is very FULL, which is strange and could indicate that you did not built a lot of troops since 1914. My manpower reserve is often close to minimum especially so late in the year because i built new corps all the time.
Do not hesitate to print money often to build divisions after divisions as early as possible.
A regular division is 50 manpower for 60 Combat Power. It looks like you have 4000 Combat power that is setting unused in your reserve.