WAB works very well for Dark Age stuff. In fact, that's probably what it is best at. WAB is basically a 'big skrimish' set (just look at the missile ranges; in a big battle set bowshot should be about the same as the frontage of an average unit).
Let's grant for a moment the extremely narrow definition of a 'big battle' ruleset given above. It still begs the question of what an 'average' unit represents in a particular 'big battle' ruleset. For example, given a foot bow range of roughly 220m, the definition given above would be true only for those rulesets that have an 'average' unit with a frontage roughly equivalent to that of a four-cohort wide Roman legion. On the other hand, if the foot bow range given is roughly 4 times the frontage of an 'average' unit, then the unit would occupy the frontage of a single Roman cohort.
WAB has a foot bow range that is 5 x the average unit frontage. And so the 'average' WAB unit would represent the rough equivalent of a Roman cohort. As a point of comparison, here is the same criterion applied to some other popular Ancients 'big battle' rulesets (all measurements assume the use of 25/28mm figures):
Ancient and Medieval Wargaming: foot bow range = 2 x average unit frontage;
Armati 2nd edition: foot bow range = 7.5 x average unit frontage;
Basic Impetus 2.0: foot bow range = 3 x average unit frontage;
Clash of Empires: foot bow range = 5 x average unit frontage;
DBA 3.0: foot bow range = 3 x average unit frontage;
DBMM 2.0: foot bow range = 3 x average unit frontage;
Field of Glory 2.0: foot bow range = 1.33 x average unit frontage;
Hail Caesar: foot bow range = 3 x average unit frontage;
Impetus: foot bow range = 5 x average unit frontage;
L'Art de la Guerre v3: foot bow range = 4 x average unit frontage;
Mortem et Gloriam 1.1: foot bow range = 2 x average unit frontage;
Scutarii 2nd edition: foot bow range = 2 x average unit frontage;
Swordpoint: foot bow range = 5 x average unit frontage;
To the Strongest!: foot bow range = 2 x average unit frontage;
War & Conquest: foot bow range = 3.33 x average unit frontage;
Warrior: foot bow range = 2 x average unit frontage;
WRG 6th: foot bow range = 3.33 x average unit frontage.
So none of the popular Ancients rulesets listed above has a 1:1 ratio of foot bow range to 'average' unit frontage. In fact, only one of them even comes close. So it is clear that other criteria, such as the ratio of movement distances to shooting ranges, are of much more importance to Ancients rules designers. Even so, all of the rule sets listed above that I have tried, play and 'feel' like 'big battles' to me. Naturally, YMMV.
