Remember the attack pattern in early FB? The fighters would climb some 1000 m on top of the bomber formation and than dive steeply attack and disengage (that's the safe way to attack also in RL). It seems to me this is not anymore working so nicely: the fighters would still dive but at a lesser angle, the result is they will stay too much in the sight of the gunners, so they will die easier. To give an example: I set 4 FW190A8 veterans with cannons attack 4 average B25 with altitude advantage of 1000m. Outcome was a disaster, I was flying no 4th in the flight and shot down 3 just because no 1-3 dived too early and were rather punched by the B25 gunners. The funny thing was that when I created that mission I considered the B25 annihilation an easy job and put some P51s arrive 3 minutes later
What's your impression? And are there some settings of altitude & speed which might help?