OK, it looks like I have to expose my fraudulent bookkeeping... First of all, I was trying to determine if Delta66's core (as in his saved file) was so expensive as to trigger the softcap, which would explain his low prestige income. As I was expecting, some units were very expensive, but this is amplified by the way deducter has set up the transports. As his mod is not yet adjusted for all these later changes, it makes for some interesting numbers. But don't blame him, it's just an interesting showcase what can happen when a balanced system suddenly gets a new variable designed for a different system. The softcap is adjustable, or can be switched off, so modders and users can breathe easily.
OK, some info about the softcap, it looks at the value of the deployed core (excluding bonus/SE) units, and calculates the average value of the units. If the average is higher than 400pp per core slot, than prestige income is gradually reduced (from 100%), up until it reaches 20% and levels out. This last point is reached when average value is 800pp or higher. I wanted to see if Delta66's core could have been worth 800pp average per slot, to see if the softcap was limiting his prestige, as I was expecting.
But we are talking about the prestige value of the units, not their purchase cost. Value is derived from is strength, and cost must be adjusted by the OS costs. There are three OS cost modifiers, I will use only two, as the first one is the difference in cost when purchasing between scenarios (cheaper) or reinforcing during battles (very expensive).
So if I assume the softcap mechanism uses the base cost in between scenarios, this leaves a base OS modifier 'OverstrengthCost' and a modifier 'OverstrengthCostPerPoint' which depends on which OS step is being valued. The OS step from 11 to 12 is a lot cheaper than from 14 to 15. These modifiers have to be multiplied to get the total value.
The basic numbers, pulled from 1.21beta:
Base OS cost modifier is 200%
OS step cost modifier for OS strength 11 is 100%
OS step cost modifier for OS strength 12 is 150%
OS step cost modifier for OS strength 13 is 200%
OS step cost modifier for OS strength 14 is 250%
OS step cost modifier for OS strength 15 is 300%
So remember, a single OS step is already worth twice the pp of a single strength point, and that is before we multiply it with the step modifier!
First off, an easy example: Delta66's core has a number of units, let's start with a Panzer IV F1, strength 12.
With deducters mod, this puppy costs 300pp, a nice round number. As this Pz4 at 10str costs 300, a single strength point is worth 30pp (10 % of 300), right?
If you wanted to get this Panzer from strength 10 to strength 11, what would you have to pay? You'd have to multiply 30pp by 200%, so 30 x 2 =60pp, and then again multiply this by 100%, so step 1 (OS 11) total is x (30 x 2) x 1 = 60pp.
To go from strength 11 to 12, you'd have to pay 200% of 30pp (=60pp) but this time OS multiplier is 150%, and total cost for this step is (30 x 2) x 1.5 = 90pp
So what is the value of a 12 strength Panzer IV F1 in deducters mod? 300 + 60 + 90 = 450pp. A little over the treshold for the softcap, but nothing shocking.
Next up, Delta66 has a 13-strength Focke-Wulf 190 A. In deducters mod, this costs 651pp (step cost = 65.1) . What it worth in total?
OS step 1 = (65,1 x 2) x 1 = 130.2
OS step 2 = (65,1 x 2) x 1.5 = 195.3
OS step 3 = (65,1 x 2) x 2 = 260.4
Total value: 651 + 130.2 + 195.3 + 260.4 = 1236.9 (rounded to 1237). Well, that's way over the softcap limit, and remember it should average the unit values, so the two units looked at so far have an average value of (450 + 1236.9)/2 = 843.45pp. So although the Pz4 is cheap, these two units together will exceed the softcap upper threshold. So to get that down again, the other units would have to be substantially cheaper than 800pp.
Surely the feeble infantry, which costs next to nothing, will make for a lower average?
Nope. Because you have to include the value of their transports as well. And in deducters mod, these can get rather expensive.
Delta66's 13-strength Fallschirmjäger are quite expensive already in deducters mod, they cost 355pp. Their transport, which Delta66 bought for them, is the shiny, top-of-the-range SdKfz 250 half-track. And these cost a modded 300pp, to represent their rarity. Shall we make a another trip to numberland?
Base cost 355 + 300 = 655pp (step cost 65.5pp)
OS step 1 = (65,5 x 2) x 1 = 131
OS step 2 = (65,5 x 2) x 1.5 = 196.5
OS step 3 = (65,5 x 2) x 2 = 262
Total value: 655 + 131 + 196.5 + 262 = 1244.5 (rounded to 1245). Now, I'm very bad at math, but if my calculations are correct I think having another two units valued over 1200pp will not lower the average.
And some other units look quite expensive as well, so I concluded Delta66 had firmly hit the softcap upper limit, so his prestige income was always going to be 20% from what he expected. But after some comments, I thought that maybe showing my calculations will help people understand better, so here they are. BTW, I personally use a simple Excel spreadsheet where I just have to plug in the base unit cost, which saves me from a lot of miscalculations.