!!! Why am I doing this ? !!!
It's just made to help you read the game more and encourage you to make trades. The difference between the worst B driver and the best is 3PP. Imagine you just signed a good Rookie (B), you could trade him for a decent C driver and at least +3PP to stay as fast as before or even faster because your other driver will get the PP trade bonus too. Get 4PP in a trade is the difference between a B and a C driver.. and it's also almost one Tier.
About the readability of the game, a simple calculation could provide you the exact pace of your car. Let's say you're a Tier 3 who bet on the right WDC last season with a driver that just became class A for this season. Your pace is supposed to be exactly 27PP without setup. Your major opponent is a former Tier 2 team who just fell into your Tier with wrong bets and a solid B class driver. His pace is supposed to be around 22PP or more, so 3 or 5PP less than yours. You only need to be at least #5 in the setup process to be sure to beat him.