I've won my fair share of tournaments and would class myself as a top player 
My biggest 'pros' are:
Know the rules. There is often a huge difference between optimal/safest scoring strategy and getting to the wizard mode or shooting what the machine is telling you to shoot. To not only have a strategy in place to get the best score, but the ability to change that strategy as the game situation changes.
(Example: You need 20mil on Met to win the game - go for Sparky MB, you need 200mil - you've got to be going for CIU). Knowing when the high value high risk strategy is your best option.
Ability to make shots on the fly! I know it's not seen as the thing to do, but if you can regularly make shots on the fly it's as important a tool as being able to live catch and cradle up - especially in multiballs.
Accuracy. Or more importantly the ability to learn a shot on a new machine that you've just stepped up to. As mentioned above - we can all become good on a machine we've played 50 plus times. The majority of the comps in Europe are single game qualifying style. You don't get to play the same machine a dozen times as you would in a HERB style qualifying. There are people who can average high scores with a very low variance in their scores, I tend to be the exact opposite, which is something that happens based on the strategies I play. Go big or go home. (Example Last years BOp, in the 8 qualifying machines my positions were somewhere in the region of 1st, 2nd, 2nd, 40th, 45th, 50th, 85th & 110th!!!). With the mid-range games I was only 1 or 2 shots from starting the stacked MB needed to get a massive score, F knows what happened with the 2 low scores.
Gaining control. In contrast to making shots on the fly. There are times when it is best to gain control and think about the next shot.
Nudging. Or I would say when not to nudge. I see people nudging just because they can, and they feel it's the right thing to do, when in fact it's not achieving anything positive at all.
Resilience. Not getting too distracted by a house ball, or 2, or by your opponent blowing up a machine. I've lost count of the number of games I've come from MASSIVELY behind on my last ball to take the win, or set the GC. I've only ever once given up on a game, or thought I couldn't make a comeback. (I was 250mil behind on Family Guy going into the last ball.)
Practise. You need all of the above skills to become second nature, so when you are under pressure in a tournament, you don't even need to think about executing them.
Above all, it has to be said that there are people who are just great at pinball, a natural ability to be able play. I hate those kind of people 
