Here is a screenshot from a decompiler of Vanilla showing a 2.66 increased range from leeway for melee attacks
mxwcfyzk3y731.png (1662×802) (redd.it)
Here is a blue post showing 2.66 yd increased range from leeway at the end of WoD
Here is the relevant portion.
Melee attack: MAX(5, SourceCombatReach + TargetCombatReach + 4/3) + IfSourceAndTargetAreRunning(8/3)
Key part there: IfSourceAndTargetAreRunning(8/3). That is the leeway. That 8/3 is 2.66, the same as was shown to be present in the Vanilla client. So we know the leeway was the same between Vanilla and the end of WoD.