The toughness of the buffs is made up by the maneuverability of the fighters. The buffs as a single box will have a hard time surviving. In the last 87 tours I have flown the B17 very little and have 9 kills to 12 deaths. SO I have lost 4 boxes to the 9 fighters I have downed.... seemingly to support your theory, but again those 4 boxes may have been the only flights I had.
It doesn't matter, your experience is still evidence for my point. The boxes that you, a single player controlled, were more than a match for the fighters single players controlled at a rate of two to 1. These numbers indicate that, on average, the fighters playing defense to your bomber offense have to outnumber you to stop you. And your number of deaths says nothing about the number of times you were actually prevented from making your bomb run, which the factor of main importance. Probably less than the number of times you lost a drone or two.
On the other hand for that same time period I have almost 200 kills of B17's and only 50 deaths to B17s. 4 to 1, easily taking out a box per fighter.
I'd like to know what "almost" 200 B-17s is...195? 185? 175?
Even so, dividing by 3 indicates that you have taken out tntire B-17 boxes 66.6 times and have been taken out by them 50 times. This is a k/d of 1.33333. Your fighter k/d in Late War Tour 167 was 1.50. These numbers would indicate that on average, an individual flying a B-17 box is slightly more likely to kill you than than the average of individuals flying everything in the MA, including fighters. And you are a relative "experten".
However, I did once wing with JG11 when they were practicing attacking large formations of of buffs in the MAs before one of the scenarios. The "Allied" bomber groups numbered in the 15-20 box area and they flew tight with in a couple thousand yards of each other. I don't care how fast you were, what angle you came in at nor how many came in from different angles to confound the gunners, everyone was swiss cheese and limping home if not down after a single pass.
In the ETO before bombers were escorted, German pilots had a field day attacking them. And yes, they often did attack even from 6 o'clock. I've seen ample gun cam footage of such approaches. Such operations were dangerous and rough on the German pilots and their planes no doubt, but they were sheer bloody murder on the bombers. In AHII, numbers clearly indicate it is the opposite.
A single average fighter will take down a single average buff group far more often than the other way around.
The hard numbers indicate that this statement is false. For this to be true, the k/d for a given fighter against a given bomber would have to be in excess of 3. In tour 167, the most popular fighter in the game, the P-51D, average firepower, excellent speed, often lingering up high, killed 685 B-17s (the most formidable non-perk bomber) and B-17s killed 273 P-51Ds, for a k/d of 2.5. Dividing 685 by 3, we get 228, which means that in tour 167 the P-51D shot down 228 boxes of B-17s, but 273 P-51Ds were shot down. Simply put, individuals flying B-17 boxes won fights with P-51Ds more often than they lost, to the tune of 1.2 to 1.
The B-24, probably the most popular bomber, was killed by the P-51D 553 times and was killed by it 173 times. This indicates that the P-51D is SLIGHTLY more likely to win a fight with a box of B-24s than lose it. 553/3=184.3 times individuals flying B-24 boxes were destroyed by P-51s, vs. 173 times P-51Ds were destroyed by individuals flying B-24 boxes. This works out to a P-51vB24 box k/d of 1.065. The total k/d for P-51Ds in LW tour 167 was 1.35. So in other words, in tour 167 the B-24 box had almost a 1/1 kd ratio fighting the P-51D, and was significantly more dangerous to the most popular fighter in the game than the average of all threats in the MA.
What these k/d numbers do not tell is on what percentage of attempts the bomber formation got through to sink the CV/level the base, whether or not it managed to RTB, which is the most important bit. Experience and observations suggests that it was way, way higher than a coin toss though.