Ricky's Rule of 72

Carl Edwards, Dale Earnhardt Jr. and Kevin Harvick are good case studies for the Rule of 72. Getty Images

Before this year's Chase began, I wanted to establish a way to determine when Chase drivers are eliminated or in serious jeopardy. So I looked back at the average Chase finishes of each Chase champion (2004-2010). This meant literally adding up their placement in the 10 races.

For example, Jimmie Johnson's 2010 Chase finishes are as follows: 25, 1, 2, 3, 3, 5, 7, 9, 5, 2. Using a little elementary math, we can determine that his "magic number" last year, the sum of his actual finishes, was 62. Over ten races, that's an average finish of 6.2.

To make things fair and eliminate the anomalies, I threw out the best and worst average finishes: 5.0 (Johnson, 2007) and 10.8 (Johnson, 2006). Looking at the remaining five, I concluded that Sprint Cup champions averaged a 7.26 finish in the Chase. In other words, drivers who keep the sum of their finishes at 72 or under are still in the title picture. Drivers who exceed 72 are, in all likelihood, out of the running.

The Rule of 72 isn't about determining a champion as much as it's about having a bottom-line number to gauge which drivers don't have a chance once we get down to the final two races at Phoenix and Homestead. Here's where things stand now:

As the table above indicates, Denny Hamlin's first three finishes (totaling 78) diminished his Chase hopes. Ryan Newman and Jeff Gordon were above 72 after their fourth race. And Dale Earnhardt Jr. eclipsed the 72 mark after his 19th-place finish at Charlotte. History says if you exceed 72 in the first five races, as these four drives have, you won't be contending. If you exceed 72 in the eighth race of the Chase, you have a little bit more wiggle room, but your chances are still pretty slim.

Who's on the hot seat besides the four aforementioned drivers? The man whose championship runs contributed most to the Rule of 72 -- Jimmie Johnson. Seven points away from 72, Johnson needs to finish second or better, on average, to stay in the hunt.

It's also interesting that halfway through the Chase, the driver in second place, Kevin Harvick, has exactly half of 72 for his combined total finishes. That suggests that he needs to do a little better in the second half if he wants to really push for a title.

The numbers also suggest that if Carl Edwards replicates his performance in the first half of the Chase over these next five races, he could be looking at the lowest combined finish total (46) in Chase history.

Ricky Craven is a driver with wins in all of NASCAR's top three series, including rookie of the year titles in both the 1992 Nationwide Series and 1995 Sprint Cup series. He currently serves as a NASCAR analyst on ESPN studio programs.