As the Imperial Army completed its encirclement, the situation on the battlefield reversed, and the advantage held by the Alliance Army quickly vanished.
Although the initial advantage was lost, overall, the Alliance Army hadn't fallen into too great a disadvantage.
The one truly at a disadvantage was only Wilton's fleet of battleships; in contrast, the other two units of the Alliance Army had joined forces, so even when facing the Empire's encirclement, they weren't in too great a disadvantage. More than that, with both numerical and qualitative superiority, victory on the flanks seemed certain unless something unpredictable and major occurred.
Similarly, if the flank engagements were bound to end in an Alliance victory, the outcome of the frontal battlefield held little suspense as well; Wilton's battleship fleet would inevitably be devoured by the Imperial Army, an unavoidable and inevitable outcome.