CONCORD, N.C. -- Chinese philosophy notes how yin and yang describe polar opposites connected in the natural world. Darkness and light, hot and cold are such examples. Extend this to NASCAR and one gets Carl Edwards and Kurt Busch.
Their differences, though, go well beyond personalities. Look at the track.
Saturday Edwards celebrated his victory in the All-Star Race, while Busch again had a frustrating night with a car that wouldn't obey his commands. It's been that way for the last several weeks for both. Edwards finishes near the front and builds on his points lead, while some of Busch's recent runs are more memorable for his rants on the team's radio.
Even after damaging his car in a celebratory slide through the infield grass, Edwards talked about finding the "positive light'' in such situations. Busch seems to be surrounded by darkness.
A year ago, their auras were flip-flopped. Busch was en route to completing a sweep of the All-Star Race and the Coca-Cola 600 at Charlotte Motor Speedway. The 600 win began a six-race stretch in which the former series champion finished worse than seventh only once.
Edwards struggled. The 600 marked the first of a season-high five consecutive races in which he placed outside the top-10. He fell to 12th in the points, the last transfer spot to make the Chase.
Then, as Busch cooled later in the summer, Edwards got hot, assured himself a spot in the Chase and won the season's final two races. Edwards finished last year fourth in the points. Busch was 11th.
As both head into Sunday's 600, they're again on divergent paths. Edwards has two wins, including the All-Star victory, finished second three times and scored six top-5 finishes.
After a hot start, Busch has one top-10 finish in the last seven races, dropping him from first in the points to ninth. Busch, who has won at least one race a year for nine consecutive seasons, has gone 34 races since that 600 win a year ago.
When one ponders the favorites for this weekend's race, they're likely to name Edwards, Kyle Busch, Jimmie Johnson or several others before they get to Kurt Busch. Saturday showed why Edwards is among the favorites this weekend and why Busch is in the underdog role.
Edwards has benefited from the resurgence at Roush Fenway Racing. Roush's Fords have won all three races at 1.5-mile tracks this season with Edwards winning at Las Vegas and in the All-Star Race, and Matt Kenseth winning at Texas -- where Roush cars took three of the top four spots.
"The Ford guys have done their homework, they've done a nice job,'' said Kyle Busch, who finished second to Edwards in Saturday's race. "I'd certainly like to have a new engine. I don't think we were down tonight, but it would certainly help to have more.''
Fords won every segment in the preliminary and the All-Star race and combined to lead 69 percent of the 140 laps run in both races.
"It's a testament to the hard work everybody's been doing,'' car owner Jack Roush said of his team's success this season. "There's a lot of discussion about hard work in this business, but the Roush Fenway guys have really, really suited up for it in the winter, and the manufacturing part is working well.
"The unsung hero is Doug Yates and [his] engine. I watched the way that engine held down the straightaway, and it was really, really, really good. A long time since we've seen our engines run as good as they did tonight.''
For as good as Edwards was during the race, it was what happened after the race that garnered as much attention. Instead of stopping at the start/finish line to do his customary backflip, Edwards decided to slide through the infield grass. When he did, he hit a dip and the car's front end dug into the soft grass, damaging the car. "[Crew chief Bob Osborne] was a little pissed off about it,'' Edwards said with a smile.
But even Osborne could see something positive out of it. "The only positive I can see here is that Jack allows us to build a new car,'' he said.
New cars can't come quick enough for Busch, who has struggled with his car's handling for much of the season. Saturday was no different. It's made the frustrated Busch even more combustible on the radio this year.
At Richmond, he stole a line from Days of Thunder, yelling that the way the car was running, "We look like a monkey [expletive] a football. The [expletive] Penske [cars] are a [expletive] joke.''
While the team has made some changes since, it likely will take time for it to give Busch the feel in the car he needs to be competitive. The question is if that can be done in time for Busch to maintain a Chase spot with Mark Martin, Greg Biffle, Denny Hamlin and Jeff Gordon outside the top-10 in the standings, but only within 37 points of Busch.
As Busch struggled early in the All-Star Race, running near the back of the 21-car field, crew chief Steve Addington asked him: "Do you want a bunch of wedge out of that thing?''
Busch replied: "Same thing as every week, dude. I really just don't care. Can't believe we're this good right now.''
About a minute later Busch asked if they could change right front springs during the break, Addington told him, no.
"10-4,'' Busch said. "Just pack the s--- up.''
Later in the race, Addington asked Busch about the right front.
"Same thing as every week, the front end doesn't turn,'' Busch said. "The front end doesn't turn. Somebody forgot to dial that in. Hell, it was awesome when nobody was racing for the first two laps. Passed half the field. Gee, then our setups kicked in. Just unbelievable.''
Busch finished 13th.
If nothing else, Busch and his team knows what won't work. The question is if they can find how to make their car better for this weekend.
Good Start:Kimi Raikkonen, the 2007 Formula One champion, finished 15th in his NASCAR debut during last weekend's Camping World Truck Series race. He drove a truck owned by Kyle Busch.
Raikkonen, who is expected to compete in this weekend's Nationwide race at Charlotte, described his race Friday as "more fun than I expected.''
He also learned a key lesson in what NASCAR drivers experience each weekend.
"It's a new thing about [so] many cautions,'' said Raikkonen, who also hit the wall a couple of times during the race. "Every time you feel that the car starts to run better then you have a caution and then it seems to take a long time before the handling comes back.''
Raikkonen also expressed an interest to run some Cup races at some point this year but noted his plans are fluid.
"Since I stopped in Formula 1, my interests have always been in many different motorsports,'' Raikkonen said. "I want to try different things and this wasn't the first time that I have been offered to come here.''
"So, I mean, if I completely suck here, there's probably no reason to come back. I mean, I don't know yet. We go day-by-day and see how it goes and what comes in the future it comes. I have no plans for next year so it's too early to think about it."
Coming Later This Week on SI.com: Dustin Long takes you into NASCAR's race control booth for a rare behind-the-scenes glimpse at what takes place in that room during a race.
Dustin Long covers NASCAR for The Virginian-Pilot in Norfolk, Va., The Roanoke (Va.) Times and the News & Record in Greensboro, N.C. His blog can be found here.