[naive]

I think the reason COD seems so much easier is because of the huge quantity of more casual players that play. Counter-strike appeals to the more hardcore crowd I think. I've always stomped servers in COD using my cs skillz to the point where I got bored with it. From what I recall, if you get a few kills in a row they give you helicopters and shit to kill even more people and then you get even more assistance, and it really detracts from the balance of the game. It's like whoever gets the first few kills is likely to get an even larger rampage and end up as the map leader due to momentum, not skill. I don't think that there is a greater variance of skill in it, so much as the game itself is designed to make certain players get more kills than others.