This is a classic case of paying attention to the wrong metrics. The unsubscription rate went up. But so did the sales. And yet, the author is paying attention to the unsubscription rate. Not the sales.
(Yes, it would make sense to pay attention to the unsubscription rate if the author shares the historical data of those unsubscribers. Did they make a lot of purchases in the past and the long salesletter is just bugging them off - which is reducing the "life time value" per subscriber?
But I don't think that data has been collected. (Or the author would have shared it with us in my opinion...) So - this to me feels like a decision made keeping the wrong metric in mind.
I do agree with you, especially when considering the life cycle of the user. Maybe NK never looked or calculated the average member value of his users. Some of these users might have reached the peak of their member cycle and decided to unsubscribe. It could have also been (as you mentioned) that the long text had "turned them off".
Nevertheless, the important factors in which he should focus on are the following:
- CRM - keeping a good relationship with his user base
- Sales - number of joins/sales made by the campaign --> which would transfer towards average revenue per email
- Maintaining a good quality list of users who are truly interested in his product --> it's all about quality over quantity, and not the other way around.
Lastly, the most important factor which NK did pick up, was that there was a surge in unsubscribes. Why was there a higher than average number of unsubscribes? He looked into it, and attempted to "win back" some of those users by sending them a personal email.
--> I personally would have added a question asking them as to why they had unsubscribed (to find out the truth behind the sudden spike in unsubscribes).
(Yes, it would make sense to pay attention to the unsubscription rate if the author shares the historical data of those unsubscribers. Did they make a lot of purchases in the past and the long salesletter is just bugging them off - which is reducing the "life time value" per subscriber?
But I don't think that data has been collected. (Or the author would have shared it with us in my opinion...) So - this to me feels like a decision made keeping the wrong metric in mind.