Seem to be completey dissasociated from the number on the map. Regardless if Attack Strength (AS) is 20 and Defense Strength (DS) is 5, or reverse, its' always 2 allied soldiers.

A better system would be to spawn allies relative to the ratio of attacker/defender strength AND also adjust the rewards as well (reward = reward * AS/DS). After all, if you came in the nick of time when they are heavily outnumbered they would be more thankful than if you arrive when they are already beating the pandorans back handly and have the upper hand.