Of course it needs skill. Does it help develop skills that are useful in the realworld? Not really. Games that promote resource management, teamwork, or coordinating several items at once promote real-world skills, but not much in CoD is applicable in the rest of your life.
But the fact that somebody who has played before will beat somebody who hasn't played indicates that at least some level of "skill" is necessary (you can argue about how to define skill, I'm not in the mood). Things like prediction of an enemies movement, analyzing the map layout to find the best locations to attack from, as well as quick reactions to respond to the unexpected all count as some sort of "skill" to me.
But now that I think about it, a reeeaaaaly good player shouldn't have to have quick reflexes at all. A good player will know his opponents move before his opponent does, and he will be able to make them move around the battlefield like a conductor controls the orchestra. But that can apply to all games, not just CoD, so whatever.