This is such an interesting take on the myths of subject lines and reporting. There is so much more that contributes to the effectiveness of an email campaign - whether they are expecting your emails, who the email is from, whether the content met their expectations and are they happy to keep receiving them? The true metrics of success branch further than the open rate (which is not an exact science at the best of times). 

Think again about what you thought about subject lines and what other metrics tell you about the interest or intent surrounding your brand, product or service.