The new replacement feature

[Volcano Man]

As the percentage of replacements increases, shouldn't the quality of the unit decrease?

No, absolutely not. The rule was not designed with this in mind and, for the most part, you are describing a use for it in the opposite in what it was intended. The intent was that higher quality units would, on average, always get high recovery. The replacements are for the lower quality units to keep up or surpass higher quality unit recovery. The other design intent was to be able to seperate nationalities of the same side which should get higher / lower strength returns.

In no way was it meant to be so complex that the engine would calculate and adjust quality levels because high replacement rates are given to high quality units, you just to assign replacement rates that are reasonable in the sense that it avoids the whole quality / quantity issue.