COD isn't really an esport, it barely has any viewers.
If any gambling site adds esports-betting, they're much better off adding the big 3: SC2, DOTA2, LOL.
Call of duty gets like 30k viewers when OpTic is streaming also Call of Duty is alot more exciting and explosive then SC2 , Dota2 etc....
and if someones site is in ENGLISH! then it is probaly looking for people who speek english most people who watch dota2 , LOL , SC2 can not speak english or have no Idea what bitcoins are!
Even thoy one community is bigger alot of COD fans have a bitcoin based knowledge so one community is bigger but one is stronger