Nick Diaz's chance to come to the UFC was a move made seemingly as much to provide Georges St. Pierre with a new, marketable challenger as it was to prevent him from following through on his Strikeforce contract which allowed him to take a pro boxing match. Diaz had a deal worked out with the well faded (and frankly never all that good) Jeff Lacy which was being shopped to different pay-per-view distributors but the UFC brought him in and gave him the shot at GSP's title.
Diaz no-showed press events and got bumped down to the co-main event to fight B.J. Penn.
Nick is now telling MMA Fighting that he regrets his decision to skip out on his boxing opportunity:
"I would have gone back to boxing," Diaz said. "If I had my chance to do it over again, I would go back to the boxing contract. It would have paid me more money, and I would have took my punches win or lose, and just do my job, fight and get paid."
"Later on, I'm sure they would have me back here or somewhere...I don't think about it till it's all over with but I would have made plenty of money in boxing and would have made plenty of money later coming back so it definitely would have worked out if I had done what I set out to do and gone to pro boxing for a while."
Back in May, when the Diaz vs. Lacy bout was being put together I talked to people involved in putting the fight together and was told that Diaz would only be making a very small percentage more than Lacy's $150,000 purse.
Diaz can still have a seven figure payday against St. Pierre if he can get by Penn. That's just money beyond what he could have ever realistically gotten in boxing. Honestly, with sponsorships this Penn fight probably nets Diaz more money than he'd have gotten in boxing unless he somehow racked up several wins in a row.
This sounds to me like just another case of Diaz having cost himself and now wishing he'd handled things differently while still avoiding coming to terms with his own mistake.