There's been much debate on ASIC quality rating and it's utility going back years. The general concensus is, while a higher number can indicate better silicon, there are many variables that go into having a decent OC and/or undervolting capability: VRMs, cooling, VRAM timings and stability, PCB quality... This point is shown with what you're seeing with your Nitro with a lower ASIC clocks lower than your Nitro with a higher ASIC rating. Similarly, I've had cards/chips with low-range ASIC rating that perform better than the same card/chip with a very high rating.
My Red Devil, incidentally, is right in the middle of your Nitros at 44.5%. From my limited testing on it so far, I'd say it overclocks and undervolts very well, but does not undervolt as well/stably as my returned MBA... which was rated at 43%.