SC2 for example does not have this problem on the competitive ladder, is this a different system?
its because SC2 both players connect to a server, in coh2 both players connect to eachother (or a peer to peer system).
the only server that is used in coh2 is for the match making then you connect to the player; its why if one player is lagging both lag. (well and obviously for your stats.)
this is to the best of my understanding anywho.