I would like to offer another reason as to why season ticket sales may be down.
It can be difficult to buy one!
A guy I work with went to buy one on Saturday morning, but the club shop was shut. It's only open Monday - Friday until 5.30. The shop only opens on Saturdays when a match is on. Also, when he went to buy it online he was unable to do so. Explanation for this is confusing, but something to do with once the fixtures have been released then they can't sell them online. We work until 6 or 7 every evening, miles away from Inverness which makes visiting the shop impossible.
If the club made it easier to buy a season ticket, then perhaps more people would have.