I have been running ICC for transmogs recently (over the last few weeks). I have noticed that exactly 0 tier tokens have dropped in the 4 weeks I have been running it. I took a break from the game around cata, so my memory may be a bit rusty. I know in TBC, the bosses who dropped tier would drop like 2-3 random tokens. I can't remember if the bosses in ICC dropped tokens 100% of the time or not. Regardless, is it unusual for them to drop 0 over such a long time span?