ORIGINAL: PzB
No idea how much pilot skill affects hit ratio, I guess it would be a pilots ground attack rating that counted the mosy here. The CAG attacking Christmas Island were probably good pilots but ground attack is hardly their primary skill.
6 forts is more than what Iwo Jima had..Allies spent weeks using a much bigger air / sea bombardment force to attempt to suppress a much smaller target than Christmas Island. When soldiers watched major bombardments they were alwas convinced nothing could survive only to learn quite the opposite when they landed.
What hasn't been mentioned here is thay disruption levels for xx tens of thousands of troops also is raised by 20-40%.
The entire division attacked has 56% disruption now.
I actually think rough terrain offers adequate protection in game, but I also think that 6 fort level should provide the same.
Generalising is difficult though...
Your last sentence is important. Forts 6 in the game are the same the world 'round, but what Iwo Jima had cannot be reproduced by Man in a harbor. Yet in the game a '6' is a '6'.
Iwo had three days of naval bombardment, with rain, and rotating ships on the gun-line. It was not a devastating effort. Air attacks were over a longer period, but in short bursts, mostly by LBA from long range. During the landings most CAS was supplied by a small number of CVEs, one of which was lost, with, I recall, three fleet carriers (maybe four) providing CAP for the amphibs and the CVEs. There was no effort at Iwo in the same universe as over 400 strike aircraft hitting the invasion sites in one morning.
Your point about pilot skill is well-taken. Maybe Andy could give you an idea of average ground skill. I'm in late April 1945 in my game, and I've done General Training for about a year for lots of my front-line pilots, except the B-29s. The carrier guys have long since reached diminishing returns on Naval. I have many CV pilots with high-40s on Ground.
The size of the island doesn't factor into the algorithm to my knowledge when it's a port attack. Everything in the hex can be hit equally, and all AA in the hex can hit just as equally. Please correct me if I'm wrong on that.
I'm not surprised you have those kinds of disruption from an attack this large. It's possible that there is an escalator for ports in the algorithm (no ports are 40 miles across, pretty much), but I don't know that. You're talking something like 400 tons of pretty well-aimed bombs in this attack, not area bombing. I think even inside a '6' bunker there's going to be some shock. It ought to wear off pretty rapidly, but I don't think this is modeled either. I think disruption decay is generalized.
The kind of numbers you have here is what? about 8 fleet-CV airwings, en masse? I'm assuming the fighters were on escort; I don't want to go back and check. If any of them were on Port too that would add to the carnage. This attack consumed a significant number of available sorties for a very large TF. I don't see the results for late war as being that abnormal. You still have full fort levels, and disruption will recover if you have supplies and HQs. He, OTOH, can't repeat this attack many times without withdrawing to replenish. It's a trade off.