Despite concussion, Earnhardt Jr. will return to full form by 2013

"This is as good of a shot at a title that I've had in a long, long time," said Earnhardt, whose best career finish in the Chase was fifth in 2004 and '06. "I believe these next 10 weeks are going to be really good for us."

On Thursday Earnhardt's bid for the Cup championship officially ended when he announced that he will miss the next two Chase races -- at Charlotte Motor Speedway on Saturday night and at Kansas Speedway on Oct. 21 -- after he suffered a concussion in a wreck at Talladega Superspeedway last Sunday. Earnhardt got caught up in the Big One in the final corner of the final lap. During the pileup, which involved 25 cars, Earnhardt was hit hard twice in the left-rear quarter panel of his car, which caused his Chevy to spin and for Earnhardt to become disoriented. After experiencing headaches for two days, Earnhardt visited Charlotte neurosurgeon Dr. Jerry Petty, who diagnosed NASCAR's most popular driver with a concussion.

On Thursday Earnhardt also admitted that he likely had suffered an earlier concussion on Aug. 29 during a tire test at Kansas Speedway, when he crashed into the Turn 1 wall after blowing a right front tire. "I knew something was just not quite right," he said of how he felt after the Kansas crash. "But I decided to just try to push through and work through it. I'd had concussions before and knew exactly kind of what I was dealing with."

I spent a lot of time with Earnhardt two weeks after that accident in Kansas for an upcoming SI/NBC feature that will air on Saturday on NBC at 1:30 ET, and he appeared as mentally sharp as ever to me. But was he 100 percent healthy behind the wheel of late? On Thursday he said he was "80-90" percent. His opening results in the Chase were indeed disappointing. After finishing the regular season tied with Jimmie Johnson for the most top 10 finishes in the Cup series (17), he recorded only one top-10 in the opening four races of the playoffs.

There's a long history of drivers in NASCAR not disclosing concussions for fear that they'll get pulled out of their seat and parked for an extended period. Should Earnhardt have sought medical treatment after the accident in Kansas? On Thursday he mentioned that he probably should have, but now he certainly deserves credit for stepping forward, even though he said he "feels fine."

What does this mean long-term for Earnhardt? For starters, he'll be closely evaluated every time he takes a hard hit on the track, which is something I'm sure he'll welcome. Earnhardt has told me repeatedly over the years that his long-term health is more important than racing, and that's why he didn't appear completely crestfallen at his press conference in Charlotte. He knows that sitting out two races is the prudent move. In fact, I wouldn't be surprised if Earnhardt, team owner Rick Hendrick and crew chief Steve Letarte all agreed that Earnhardt should stay out of the car for the rest of 2012 and not take another lap around a track until offseason testing in January.

Like an NFL player after suffering a significant injury, drivers can become tentative on the track after being involved in a serious accident. Jeff Gordon, who has been in more horrifying wrecks in the last few years than anyone else in the sport, certainly doesn't put his car in harm's way as much now as he did, say, when he was winning multiple championships in the late '90s.

But I don't believe this will be an issue for Earnhardt. The force of his crash at 'Dega was only 20 Gs, which, while violent, isn't off-the-charts. And remember: Earnhardt had every reason to be gun-shy behind the wheel after his father passed away at Daytona in 2001, but that never happened.

Now at age 38 (his birthday was Wednesday), Earnhardt is still in the prime of his career. The Chase didn't go as he had planned, but 2012 will still be remembered as the year Earnhardt became relevant again. He won for the first time in four years, was consistently in the lead pack, and, as he told me, "was in the conversation again."

My sense -- after all the chats I've had with Earnhardt, his crew chief, his owner and his family members over the last few months -- is that as long as he's 100 percent healthy (and his doctor believes he will be soon) his performance shouldn't drop off in 2013.

"This is a fickle sport," Earnhardt told me recently. "Things can change just so fast. You can be on top one day and the next it's all falling apart and you're left wondering what the heck happened. It can be tough, man. Really tough."

Certainly it is right now for Earnhardt.