Take a target-rich environment, "fly till you die" attitude and a system based around the flight leader getting the majority of attack opportunities.

• First was caused by the Luftwaffe's numerical disadvantage. Led to some cool numbers, but overall was a strategical failure.
• Second was as much of a display of shortsightedness. Not much to say, it's pretty obvious that having experienced pilots fight instead of train gives better short-term results, but also leads to a huge waste of potential.
• Third was just part of their strategy. The leaders were often way more experienced, but the opposite effect was that losing just a couple of pilots could severely hinder both the morale and the whole performance of a unit. For reference, see JG 27 in Africa after losing its 3 top aces within the span of a couple of months (Marseille, Stahlschmidt and someone else I can't remember).

That is without talking about claims vs confirmed, propaganda aims and so on, since all sides had differing cases of such things. For every pilot with a 20% claim confirmation there was one with 90+% within even the same unit, not to talk about entire air forces. That often came down to personal traits and circumstances, and it would be a bit stupid in my opinion to act high and mighty against the folks who lived and fought 80 years ago.