Missed races too much for Dale Jr.

Editor's note: An explanation of Ricky's "Rule of 72" can be found here.

The Rule of 72 tells us that Dale Earnhardt Jr. was already facing an uphill climb to stay in contention in the Chase for the Sprint Cup. Earnhardt currently has 49 points under the Rule of 72 -- that's the sum of his total finishes minus his three bonus points -- and he would have needed an average finish of 2.6 to remain in the hunt entering the last race at Homestead.

So Earnhardt's difficult decision to sit out two races while recovering from concussion symptoms effectively takes him out of contention for the Chase, even though he's not yet officially eliminated by the Rule of 72. It's not realistic to expect he could make up so much ground after missing two races. And it's difficult to envision Earnhardt putting two or three race wins back to back when, in his career to date, he has never won back-to-back races and his longest streak of top-5 finishes is three races.

Earnhardt is a very talented driver and I think he's done a very good job this season. But before Earnhardt made his decision, I had him among six drivers in the middle of the pack who could be eliminated from contention for the Chase with a bad day at Charlotte. The other five on that list: Kevin Harvick, Tony Stewart, Martin Truex Jr., Jeff Gordon and Clint Bowyer.

The bottom line for Earnhardt, Biffle and Harvick is they simply haven't had the start required to win this year's title. Harvick, for example, has no top-10s in his first four races. He's been remarkably consistent, but consistent just isn't going to keep pace with the three drivers at the top of the standings: Brad Keselowski, Jimmie Johnson and Denny Hamlin. Those three drivers have the speed to battle for wins each week. They are the three drivers I believe will settle this championship.

Before I close the book on Talladega: As bad as a 17th-place finish might seem for Johnson, things really could have been a lot worse. What you fear in the Chase is a finish in the 30s. And although he was caught up in the wreck, getting out of Talladega with a 17th-place finish is manageable.

Brad Keselowski was the big winner, finishing seventh. He finally swings to positive in total points under the Rule of 72 -- entering Talladega, he was at minus-one, thanks to his bonus points. Now he is at six points after four Chase races, and he controls his own destiny.

Keselowski's performance reminds me of Hamlin's Chase run a few years ago. This is the best chance Keselowski has had at a title, and he's managed it very well so far. And as a team, the No. 2 has the ingredients for a championship. They have the resilience, they have the speed, and they have an ability to find ways to win -- whether it's fuel mileage at Dover or saving their best for last at Chicagoland.

In these last half-dozen races, I still believe we're going to see a real push from Hamlin. He's got solid stats at the Chase tracks from here on out. While he has not been as efficient as Keselowski, I think he's actually had more speed. And Hamlin has experience with being in this position, having lost the championship to Johnson two years ago. I absolutely subscribe to the belief that in most cases, you have to lose a championship before you can win one.

Although Johnson had a great start to the Chase, he hasn't won a race yet. Remember that he's won a race every single year in the Chase and logic says he's going to win again, so I'm on Jimmie Johnson watch in that regard. And quite frankly, wins determine championships.

I also think Kasey Kahne is going to climb back into the mix. He took a blow at Talladega and has back-to-back finishes outside the top-10, but he can correct that with a top-5 finish this week.

While we're talking about Hendrick Motorsports drivers, what about Jeff Gordon? He had the worst start of any driver in the Chase, finishing 35th at Chicagoland. But since then he's finished third at New Hampshire and second at Dover and Talladega, leaving him in much better position -- not back in contention yet and still at risk, but not out of it.

The answer for Gordon lies in the numbers. If he can continue his run of success, it's not unreasonable to think that he could string together top-5s throughout the Chase. There aren't many drivers capable of doing that. And quite frankly, that's what's going to be required of Gordon if he's going to win this year's title.

It's also reasonable to think that teams in the Chase field are going to have mechanical issues. It's the one aspect of this sport that keeps crew chiefs awake at night. They know they can prepare their car to the best of their ability and teams can practice pit stops until they're exhausted. They can control the overwhelming majority of their destiny in terms of preparation. But there's a mechanical risk with every event. There are certain parts on the car that are manufactured outside the race teams. And that is the one element that's next to impossible to manage or control.

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.