Playing multiplayer is something totally different from playing solo. We all know that. But here's the deal, when you play multi, here's what happens in 1v1 matches:
1. You get to know where the other player is (looking at his screen or using radar, it's the same)
2. Now that the other player has found you (because you probably shot him), he knows where you are
3. You both start shooting at each other, using strafe, using manual aim, whatever
4. One of the two will get killed
5. The other one starts running, hoping to get closer to the enemy spawn point for an easier kill. And then, one of the two will happen:
6.a: you kill your enemy easily and runs (go back to 5)
6.b: your enemy gets a gun and shoots at you (and it goes back to 3)
It's preety simple. Unless you do some naughty stuff, like shotting through doors, glasses etc, it's preety much the same every match. That's why we can't ever say that there's one or a couple of best players around. We all know how to shoot and strafe, so it goes to knowing the level a little well and how to surprise your enemy with something totally crazy (like slapping or anything like that). And with that, if we get like 20 players around here and put us all together playing one thousand 1v1 matches, the results will be even.
That not counting knowing the spawn points for every level

I remember having some matches with Laércio where the match got decided with the first kill, ending like 20-1 or close to it.
That's why a 4 player match is more interesting, in that case. You have to know where to get the better weapons, look at 3 other players' screens, know how to hide and get an easier frag after, know how to manipulate lag (haha), etc. But in 1v1, I guess we can't say who's the best, even after 50 meetings.