Tony hit all 3 of my thoughts.
1: Experience is key.
2: Reflex comes into play next-it's not exactly "timing", but can make up for bad timing if you have significantly better reflex.
3: Being able to step back and actually observe your opponent, engaging the mental aspect of a fight, adds that.
I put it in that order as 1 most important to 3 least important, but: In a sport fight I'd guess 3 can come before 2 because you've had time to evaluate your opponent and get a feel via sparring partners mimicking them for instance. So you engage the mental aspect more. But in a street fight where it's over quick and you haven't had that chance, based on my experience it comes down pretty much purely to experience and reflex, and analyzing doesn't really come in to play as much.