Your opponent would not have a possibility to win if you had beaten his fleet. The only reason he was mathematically within range is because you either chose not to attack, or couldn't beat his fleet.
Assuming he used 5-man squads on attack, he could earn:
6x 60 points for each battle = 360 pts
Top zone Conquer points = 300 pts
Bottom zone battle = 64 pts (5 ships total, 2 blanks)
Bottom zone Conquer points = 155 pts
For a total of 879 possible points on offense.
Your minimum points for defeating his fleet would be 16 points (3rd win, single ship remaining) plus the 155 points for conquering the zone. There would be no way that he could beat you.
That's why players who set no defenses at all cannot win the round vs an opponent who set defenses - there's too large of a point deficit. In this case you left points on the table, and could have lost as a result.
