For every action, so states Isaac Newton's third law of motion, there is an equal and opposite reaction. And in NASCAR, when that action has to do with Dale Earnhardt Jr., the equal and opposite reaction usually comes from Kyle Busch.

... the bottom line is that Earnhardt's free agency and subsequent move to the Hendrick stable is effectively what led to Busch's ouster, and Busch has thoroughly outperformed his successor in every way since the move was made.

That's certainly the way it seemed last week at Dover International Speedway, when the current and former Hendrick Motorsports drivers traded barbs through the media, then briefly exchanged words in the drivers' meeting prior to the Autism Speaks 400, and added an entire new level of intrigue to the saga involving Earnhardt's change of crew chief. Who knew that when Rick Hendrick hired NASCAR's most popular driver, he was also laying the groundwork for NASCAR's most intense feud.

This latest chapter began Friday, when Busch was asked what he knew about Lance McGrew, whom he's worked with briefly in the past, and replaced Tony Eury Jr. atop the No. 88 pit box last weekend. "He's got his hands full having to deal with what's going on," Busch said, "and if Junior doesn't run well, then he's going to be the problem again. It's never Junior. It's always the crew chief."

Within minutes, that comment was splashed across the Web, routing Junior Nation into another state of anti-Busch fury. And yet, Busch taking potshots at Earnhardt's somewhat disproportionate popularity-to-performance ratio is nothing new. He's done it before. He'll surely do it again. And in all honesty, it's hard to blame him when he does it.

Now, you may not like Kyle Busch. You may think he's childish and whiny and immature. Fine. But if there's anyone in NASCAR who has the right to feel wronged, who should and does take every opportunity to point to his sport's equivalent of a scoreboard so everyone can see what the tally shows, it's the driver of the No. 18 car. No, he didn't fit at Hendrick. In retrospect, that much seems obvious, and you have to wonder how much longer he might have remained there even if Earnhardt had not become available. But the bottom line is that Earnhardt's free agency and subsequent move to the Hendrick stable is effectively what led to Busch's ouster, and Busch has thoroughly outperformed his successor in every way since the move was made. (Continued)