I admit that my statement about if you change anything (such as heavy cruiser instead) was a sort of zen-based thing. In other words, Detmers skillfully wrung about all the luck he was going to get out of a situation that was so delicately balanced that if you change one thing then Detmers just has to run out of luck!An 8 inch gun cruiser - Detmers loses? Well if it was HMS Australia with Burnett in command, identical scenario, what do you think? Bigger target = better chance of both of Kormoran's torpedoes hitting......
Although I agree with you and others who say that the pre-war US heavy cruisers would have clearly been best, I'll take a stab at how a County Class might have also been enough to change the balance. I didn't research this very well but perhaps it's some food for thought and things worth a closer look.
1. The recent Sydney Report notes that among the defects in Sydney was concentration and exposure of the all the communications wires etc, in unarmored tubes. It appears that Komoran's first salvo took full advantage of this and operationally killed Sydney. Perhaps Counties had better protection for these things or disbursed it better.
2. I did see that the Counties' bridge platforms where the command, control and communications were centered (including the leadership's living brains) had thicker armor than the Leanders (not much, I think maybe 1 and 1/2 inch vs. 3/4 inch). Off the top of my head it appears neither can be said capable of stopping a 6 inch round. But one is still measurably better than the other, and may have provided enough additional protection to leave something intact or somebody alive and make a crucial difference in the amount of CCC remaining after the first salvo.
3. The CCC spaces on the Counties' bridges looks to be considerably larger and would require the first salvo to destroy, and kill people all over, an appreciably larger area to totally disable CCC.
4. As to the torpedo damage, perhaps the Counties were better subdivided or otherwise more able to take the blow and still float. Not only tat, but the key seems to be the disabling of the CCC on the first salvo, not the torpedo hit, given that Sydney continued to float afterward and could have fought and maybe even survived if CCC was not disabled first.
5. But it sure looks like there was no difference in the weak turret armor between the two classes.
If I'm going to argue appreciable differences, I have no choice but to agree that that the greater bridge armor on the New Orleans class really would certainly make a difference! It certainly would offer a real increase in CCC protection against 6 inch shells.
You said you have your own thoughts on what happened and I'd like to offer a few of my own to kick around. Some might seem far-fetched but Sherlock Holmes said that when you rule out the probable what remains must be considered no matter how improbable. Note that Nos. 1 and 3 fall on the side of tending to absolve Burnett, except for the strict liability that comes with the doctrine of general command responsibility.
1. Burnett suddenly takes ill during the chase, and before the approach becomes so close. The XO is in his battle station in the rear secondary control and unable to effectively and timely take hold of the reins. So command suddenly and at the worst time falls on number three whose battle station is on the bridge vice Burnett, and who also happens to be an idiot.
2. Burnett and the rest of the command staff on the bridge are so busy arguing about which of the competing paths to follow (seize prize, assume it's a raider, make sure it's not friendly) that they loose track of what they are actually doing. The Sydney report discusses the conflict between these goals and the resulting inconsistency on the operational orders and doctrine for such situations. Burnett prior to taking command had a desk job that involved him directly in these matters and perhaps he knew too much and saw too many choices instead of one clear route. I can't recall what the report said about prize money and perhaps this wasn't a possibility, but if it was, then perhaps this potential financial interest would cloud judgment.
3. Some critical CCC component fails at the worst possible time, just before Sydney passes the point of no return. A critical positioning or firing order is not transmitted from the bridge.
4. A mutiny! (Now I'm really stretching it)