Their numbers are not all perfectly solid though.
Marseille reported 17 victories in a single day against the RAF/DAF. The British lost 8 aircraft in the area that day, and on the home front only one.
Have been doing a little research on LW claims on RAF aircraft vs. the actual RAF reports. Sometimes they are accurate, sometimes double and sometimes total nonsense (1 damaged aircraft successfully RTB becomes a few destroyed).
I met the old LW ace Gunther Rall (3rd on the list with 275 kills) last May, and over a cup of coffee I could not resist teasing him a bit with these numbers. He was firm on the opinion that they were absolutely solid.
Well, solid or slightly inaccurate, their numbers are high. Ralls as well as the others approach to combat, especially in the latest years of the war may explain how they got so many kills. Simple reason: plenty of targets, many of those russians with either primitive planes or little experience, and finally, LW survive tactics, for many of the best looked after themselves, - a dead pilot shoots no enemy planes down. Rall: "We would not attack unless we were at advantage"