Maybe it was because, at 6-foot-3, 263 pounds, Shane Carwin is nearly the same size as, and actually has bigger meat hooks than, Brock Lesnar.
Maybe it was just a savvy promotional move for Carwin, an unbeaten, top contender for Lesnar's Ultimate Fighting Championship heavyweight belt.
Or maybe the "Colossus from Colorado" really was so outraged at Lesnar's antics at UFC 100 he couldn't contain himself.
Whatever it was, Carwin pulled no punches on his personal blog, hammering Lesnar for taunting a fallen opponent, tossing middle fingers at the Mandalay Bay Events Center crowd in Las Vegas and acting like anything but a respectful champion Saturday. After a stern talking to by UFC president Dana White, Lesnar apologized for his actions. Carwin was apparently unmoved (he didn't return a message seeking comment).
"The flipping off of the fans that just lined your pocket with millions of dollars is just LAME," Carwin wrote. "He may be a champion but he has a long ways to go before he earns the respect of a champion."
It got better, with the old school Carwin, who sports an 11-0 record, lecturing Lesnar like he was a little boy.
"The fans are why we do this Brock, this sport is not about fat paychecks and drama. It is about hard work and sacrifice for a shot to do what you did [Saturday] night. It doesn't matter how much money you make if you can't earn your peers respect and the respect and love of the greatest sporting fans in the world.
"Every autograph I give, every hand I shake I am thankful that you give me the opportunity to be a part of your world. This is the greatest sport in the world and most of the athletes in it deserve the love and respect they get and some just don't get it."
The mechanical engineer wasn't done yet. Next up, a shot at Lesnar's pro wrestling background.
"We have no scripts in this sport, no pre-determined earning amount and no pre-determined outcomes. It doesn't matter if you win or lose; it matters how you win or lose."
And to think Lesnar couldn't deal with Frank Mir making fun of his jiu-jitsu defense (which was once, admittedly, weak). This alone will fuel him through a long Minnesota winter of training. And who knows what else Carwin has in him?
Carwin takes on Cain Velasquez (6-0) in October at UFC 104 in Los Angeles. The winner gets a shot at Lesnar for the title, White has announced.
If it's Carwin (no small feat against the excellent Velasquez) then this wouldn't just be an intriguing fight, but suddenly a personal one. Carwin, like Lesnar, is a former collegiate wrestling champion. They're about the same size; although Carwin's massive 5-XL gloves are actually two sizes larger than Lesnar's. It's one reason none of Carwin's opponents have lasted past the middle of the first round.
Which is good because the indomitable way Lesnar has looked of late, it's going to take a special mix of size, speed and skill to challenge him. And he's only getting better.
Carwin doesn't sound concerned. Not about Lesnar and not about rattling his cage. His rip job will be appreciated in traditional mixed martial arts, where discipline and respect for an opponent is still paramount.
Since arriving from pro wrestling, Lesnar has expressed little concern for such things. That's his right and it'll earn him plenty of supporters who love every second of it. If he wants to sneer and snarl, if he wants postfight interviews complete with sponsor bashing, cheesy histrionics and juvenile statements, there's only one way to stop him.
"From leaving the venue all the way to the airport I have had fans of the sport ask me to take out Brock Lesnar for them," Carwin wrote.
The UFC will focus on pursuing the world's No. 1 heavyweight, Fedor Emelianenko (30-1), who is approaching his final contracted fight with the UFC's rival promotion, Affliction. That takes place Aug. 1 in Anaheim, Calif.
"We'll end up getting that deal done and then we'll do Brock vs. Fedor and we'll do a huge fight," White said.
Time will tell on that. In the interim, a contender is waiting to earn his shot and then possibly take the trash talk to a whole new level. That's what Brock Lesnar has brought to the UFC, visceral reactions all around.
Some loathe him. Some love him. Everyone wants to see what happens next, a string of big pay-per-view cards almost all but assured.
Now here comes a sizeable challenger, issuing preemptive blog posts and lectures to the champion on sportsmanship, humility and class.
Shane Carwin is itching for a fight. You can rest assured, after this, Big Brock will be too.