109 cant do XXXX anymore.

[Strike]

I think this once again points out how important pilot skill is. Think of the variables...

no 1 - When stalling vibration/turbulence starts most rookies will ease off the turn, whilst aces know they have a little more turning they can squeeze in.

no 2 - Perhaps some pilots struggle under high G-loads, and prefer not to turn tighter than what's already uncomfortable for them? (even though their lives are at stake)

no 3 - Some pilots probably weren't even aware that they were being chased/fired upon until the damage was done. (Perhaps the target was focusing on something else and turning towards it more gently than if in a dogfight).

These are just a few factors, but you get the idea that whilst we have the luxury of flying these planes in many sims and comparing them, the real pilots probably had little clue/knowledge about enemy planes initially until they saw them in combat. And what little evidence of performance they could draw from in a stressed/heated dogfight was probably highly rough estimations from subjective points of view.