I'm pretty decent at most games. I'm best at FPS', decent at most sports games and fighters, and not bad at racers.
When I first got cod4, I wasn't very good. I varied wildly, but usually would be just under 1:1. I kept playing, and got better. Not much better, but an average game would give 1:1, and I varied around it. Then I stopped playing it much for a while, and went through a phase of palying mostly single player. Came back to it a month or two later, and it just clicked. My play was a lot more focused. I was doing much better, and after playing it more, got pretty good. I'd top the scoreboard almost every game, usually by a fair margin. If not for points, then almost always for kills, and K

. There was a phase where it'd be unusual for me not to get a 10-15 kill streak, with 20+s every 10-15 matches, and I often got 2-3 helicopters a match(I played domination).
However, I got frustrated more. The flaws in the game(which aren't really that big) started to bug me. Also, I didn't have much to work towards(not bothered prestiging, had everything I wanted, etc), and that probably played a part too. I also got tired of the maps. When iI didn't know them well, it was always interesting, trying new things, exploring. Likewise with the classes. Now I only play occaisionally. When I do, i'm not as good as I was. My K

is usually still good, but I don't rack up the kills quite like I used to. As well as this, my connection rarely seems as good as it was, and I still get frustrated with the minor annoyances of the games.
I think the real thing that made it click, was I started realising what I could do better, and played more tactically. Now I've gone back to it, I don't really. Not to the same degree. I do play with some tactics, but I don't play as meticulously, or with the same patience. I don't check all my corners, and will run from place to place, regardless of the fact there are places that cover my position, or just run into buildings blind. As a result, i die a bit more.