Low morph but high count

My DH went for his second SA. It came back 3% morph previously 4%. Recommended IUI. I'm confused why count doesn't matter here. He had 700M (230/ml) which even at 3% is 21M good looking swimmers. If he had 60M count but 5% morph he would be considered normal and yet only have 3M normal swimmers. His motility was 50% forward progression. Surely all results should be considered together but his has not been the case both times, what am I missing? And why when getting results do I always end up just sitting there nodding like a fool and forgetting all my questions!!  Appreciate any info you may have 😊