I'm not sure I understand how they are measuring quality in these sperm. The article mentions that they are now rejecting 80% of their candidates based on the s

I'm not sure I understand how they are measuring quality in these sperm. The article mentions that they are now rejecting 80% of their candidates based on the simple fact that their sperm is not up to the same standards they set years ago. What if their standards are flawed? Is there scientific proof that straight-moving and quick sperm is of higher 'quality' or 'healthier'? Is the sperm bank promising me a strong child that will grow tall or what is this quality metric in fact measuring?