Your query got me thinking about how some clans could possibly reach that level of kills and tag capturing. 4K is a lot and I would expect that level to be attained by the best.
So I did some youtubing and came across this http://www.youtube.com/watch?v=MVFl0jHy_o0
Seems that there is boosting also going ahead for clan ops. I would suggest noting the clan that was boosting and reporting them. This is very shameful, can we not compete honestly anymore?