Getting blocked on Cho'gall?

http://www.worldoflogs.com/reports/bnom20khyjc9o13t/details/5/

I noticed I got blocked a bunch on Cho'gall last night. How is that possible? I'm over the hit cap (but a decent amount.. I'm being lazy about reforging). Am I missing something?
Our ranged attacks are still subject to blocks. Be in the 180 degree cone behind a boss when possible.

Unfortunately, it's not always possible.
I was behind the boss almost the entire time.. it must have been the shots I fired while he was running towards the tank at the start of the encounters.

I agree it has been around for a while.. I suppose I just never looked at it before really. Until now I hadn't considered the above (that all the blocks were at the beginning of fights) so I'm content to let that rest. Thanks for the reality check! :)