I'd like to suggest that those tiers depend on players' diaries, rather than the previous tournament activity. So, for prize tournaments, the tiers would depend on prizes score in the diary (or, maybe, the top prize that the player can hit?), for PvPs/Bastions/Presidios the tiers would depend on off+def score in the diary. For upgrade tournaments, total exp or level (for all purposes, the two are the same thing).
The current system would work fine if it depended on much longer time spans, maybe the last 6 months of tournaments. The way it is now, it is quite unbalanced.
On an unrelated (but still topic-related) note: I really liked the gift this time. It was a pleasant surprise, and much better than the previous one (for St. Patrick's day, I think). Thank you for that one, Plarium!