Shop Talk: Atlanta

DAYTONA BEACH, Fla. -- In basketball, the true measure of a point guard is the player's assist-to-turnover ratio. In baseball, every pitching coach keeps a close eye on strike-to-ball totals. And now, NASCAR has a ratio to analyze performance: Pass Differential.

The Pass Differential is the number of times a driver has passed a car under green-flag conditions compared to the number of times he's been passed.

The Loop Data stat has proved useful and interesting, especially in this young season. Though the Nextel Cup year is just three races old, two drivers have had to make significant comebacks after dominating a race.

In the Daytona 500, Tony Stewart was forced to the tail end of the longest line for speeding on pit road. No big deal. Stewart made his way back to the front 67 laps later.

The same occurred last Sunday at Las Vegas. On Lap 108, Jimmie Johnson suffered a pit road penalty for an "outside half pit box tire violation." He, too, was sent to the tail end of the longest line. And just like Stewart, Johnson clipped off driver after driver to make it back to the front. It took him 127 laps.

The Pass Differentials in these two instances are hugely important.

Take a look:

1. At the Daytona 500, from Stewart's restart at the back on Lap 83 to when he retook the lead on Lap 150, he had 67 Green Flag Passes. He only got passed 29 times during that span. The Pass Differential was a 38.

2. At the UAW-DaimlerChrysler 400, Johnson was forced to the back on Lap 113 and though he hovered around the leaders shortly thereafter, he didn't re-take the lead until Lap 240. Johnson made 62 passes compared to the 44 times he was passed during that span. The Pass Differential here is 18.

But looking at Pass Differential doesn't only make sense in these two instances. It's worth a look whenever a driver comes back from a poor qualifying effort. Or whenever a driver loses spots in the pits while under caution, but comes back for a top-10 finish.

Look at it this way: The Pass Differential is the stat equivalent of a battle scar. It shows just what a driver went through in a given race.

Below is the top-five Pass Differentials since the stat's origination in 2005.

Johnson accomplished another impressive feat at Sunday's race at Las Vegas Motor Speedway. He became the second driver this year to win a race after entering it with the top pre-race Driver Rating. Coming into last Sunday's race, Johnson had an average Driver Rating of 131.4 at Las Vegas over the last two years (the mark was more than 16 points better than second place Kyle Busch's 115.2). Kenseth is the other driver to win a race after having the top pre-race Driver Rating. He did it at California. Last year eight drivers who had the top pre-race Driver Rating won that particular race.

This Sunday's Nextel Cup race at Atlanta Motor Speedway will be very important for many drivers. After next week's race at Bristol Motor Speedway, the drivers who are in the top 35 of owner points each week will be guaranteed starting spots for the remainder of the season. Some marquee drivers -- Dale Earnhardt Jr. and Kasey Kahne, for instance -- are on the bubble. Luckily for those two, the race at Atlanta comes at exactly the right time.

Both Earnhardt and Kahne have victories at the Hampton, Ga. track and are near the top of the all-important Driver Rating and Average Running Position standings.