Hand-eye coordination is a given, it's a skill index on it's own, but I'm talking beyond that as well.
The more restrictions you place on a pilot in terms of quick reflexive actions the more predictable they're going to end up being.
Unfortunately, I've been a gamer my entire life and most of that time a clan/squad/raid/guild/whatever, leader (well ok, most = ~14 years), 'thinking' about enemy strategy is something I've done all my life, I'm not as good at it on RTSs as I should be, but most other games, especially when the human element is the bigger influencing factor in tactics and strategy on the battle field, I /tend/ to dominate.
For example, in WoW - a game that is highly competitive and very complex (leading to some major balancing issues in PvP, but anyway), when the Arena was in it's first season my battlegroup was europes most competitive, I was the strat/tactics guy for my team and we basically just took other teams to pieces, with a comp that wasn't very powerful, we ended up #1 for season 1, though we couldn't go to the regionals because of the nationalities of some of our team members.
Live tactics being formed to manipulate people into a dead end of abilities/cooldowns or just break up the flow of their nukes or what have you to leave them in a vulnerable or exhausted position, and that's monitoring my own performance whilst noting the complex behaviour of 5 hostiles who have anything between 10 and 40 'main' abilities, and 4 of my own team, managing their ventrilo comms input + macro fire, and administrating them with my own instructions at the same time.
"Simple" Physics estimations and player prediction at the same time really isn't hard, especially in an environment as restricted as a flight sim.
This somewhat applies to FreeSpace 2, quite a lot of the time I can, moreso in the past than now, I could fly in a way that would subtly put a player where I wanted them to be even if they didn't want to make that choice, and then abuse the snot out of them due to it.
It's even easier in most 'realistic' sims, though I can teach most people to do the basics of it in FS and probably not so easily in those games.
If you want to see 'thinking' 1on1 skill go watch a star craft tourny.
Squad based fighting in FS2 has absolutely no equal of all the games I've played, which is a great many.