As you add more to the situation in which combat takes place, things other than DA skill can become very important.
In scenarios, for example, the characteristics of fights can be very different, and things that don't play a role in DA can be very important: handling of a plane at very high speeds, aircraft top speed, ammo load, duration aloft, squadron-level tactics, for example. Some planes that would be at a large disadvantage in one-on-one DA fights (190A-5 vs. Spit IX, P-40 vs. A6M2, for example), have advantages in the same matchup in scenario environments. Scenario fighting can be a lot different than the MA, too. Situational awareness, knowing how to handle your plane at very high altitudes, knowing good group and many-on-many tactics, for example, is much more important in scenarios than in the DA and even the MA. If you are a leader of a squadron or group, having a knack for finding or anticipating positioning of enemy groups, and accomplishing goals instead of getting pulled into fights that don't further the goal can be very important.
That being said, folks who have the highest number of kills in scenarios are people who probably are or would be quite good in the DA as well -- they have great mastery of their aircraft overall, as well as the numerous additional skills useful in scenarios.