Here buddy, this is lag comp explained by an ex-IW, now respawn dev
http://www.respawn.com/forum/viewtopic.php?f=11&t=3521&p=60400#p60400
As you can see, ping is still king. Everything that people mistakenly refer to as lag comp (barring the oddity of host disadvantage) is purely down to ping to host/server. The fault for many many MANY complaints lies at the door of matchmaking, or something within their setup.