Nicely said Bill, but you left out luck of the draw is a plus too.
Placement in a heat race can make a big difference. If you are in the first heat where you race one or two of the lanes and then sit out till you cycle back in it can throw you off. If you get placed between two really good drivers it will usually help because you can see how they are driving. If you get placed next to a slower driver it can affect you as you need to take time to find a safe place to pass, especially if they are trying to play nerfing games.
In Salem, placement can really change your finish position. If you cycle through with better drivers you will have a hard time winning a heat or even staying on the lead lap. If you cycle through with drivers of your ability or lesser you have a better chance of winning heats and scoring better. An Expert racer running against Amateurs in a race is more likely to finish first with more laps. If it's a race that stops when the first person reaches a certain amount of laps, Amateurs will probably never get a chance to get the maximum laps possible running against Experts. And the Experts who gets to run against the Amateurs, gets a boost over the other Experts who only run against other Experts. Since you only get credit for laps completed, with the winner getting 30 and everyone else 29 or less, luck of the draw can be huge.
So, some times Luck, either good or bad, plays a factor too. My two cents worth. Well, maybe a nickels worth. Feel free to throw back some change! 