In campaign games that are driven by boardgames, the various leaders are frequently given skill ratings of one sort or another. Since DBA does not support this directly, we need some mechanism to capture the intended effect. As a general rule (pun intended), the campaign game scenarios I put together use a re-roll mechanism.
For each positive leader-quality point, that leader can re-roll any one die roll made for troops in that leader's chain of command. For each negative leader-quality point, the opponent can demand a re-roll of any one die roll.
If the boardgame driving the campaign differentiates between strategic and tactical skill, the campaign rules should differentiate between strategic die rolls (for example, terrain placement) and tactical die rolls (such as PIPs and combat resolution).