If Calder gets the exact situation he wanted, then why does he lose? Incompetence, bad luck, suicidal tendencies, or did he willingly engage with his fleet at a disadvantage? If the latter, why?
The situation he wanted was a brutal brawling match between his Destroyers and Steele's. He is, in many ways, very GTVA-like in his thinking: Where the GTVA is looking for a Lucifer or Sathanas whose destruction will mark, if not the end, then at least the turning point of a conflict, Calder is looking for Steele. He wants, metaphorically speaking, to have a battle of champions to decide the war.
Calder thinks he has a chance to win this fight. He believes that, if he can get into a close-range fight, he can nullify the GTVA's advantages; Using his superior maneuverability and (individually) superior strikecraft to suppress the immense forward firepower of Atreus
long enough for his ballistic weaponry to inflict crippling damage on the other side.
Unfortunately for him, Steele is just as adept at reading a tac plot and coming up with countermaneuvers as he is -- And unlike Calder, who has to keep the GTVA ships in range and under fire for a long time to inflict significant damage, Steele only needs a small window of opportunity to do the same to the UEF vessels.
The moral of the story is that, even when you do manage to create the most favourable situation you can, victory isn't assured.