When Nick Diaz steps into the Octagon to fight at UFC 137, it will be for the first time since November of 2006.
A lot can change in five years.
When Diaz first arrived on the scene in the UFC, he did so with a reputation as a jiu-jitsu specialist. That perception soon changed following a shocking knockout win over Robbie Lawler at UFC 49. Still, Diaz was far from a polished product.
Although Diaz was budding as a striker, even judo specialist Karo Parisyan was able to have some success striking with Diaz by barging in and throwing wild and reckless punches.
Sean Sherk and Joe Riggs also managed to have some success on their feet against Diaz. Sherk managed to out-box Diaz outright by getting inside—where Diaz's long limbs became a disadvantage.
Still, it wasn't any striking deficiency that left a lasting impression with fans: It was Diaz's lack of defensive wrestling that people remembered. Other fighters like Diego Sanchez would take Diaz down and end up winning on points.
Diaz attributes his losses in the UFC to his willingness to fight off his back, which didn't appeal to the judges, even though he felt like he was being the more effective fighter.
In fact, Diaz has gone as far as saying that he's never "really" lost a fight in the UFC.
Five Years Later
Fast forward five years, and you'll get a much different picture of Diaz that varies depending on who you're talking to.
Diaz supporters will tell you that Diaz has transformed from a mediocre boxer to one of the best strikers in the division. This is evidenced by his wins over strikers like Paul Daley, Marius Zaromskis and Evangelista Santos.
They'll tell you that in the last five years Diaz has been promoted from blue belt to black belt in Brazilian Jiu-Jitsu (BJJ), and that if somebody tries to take him down now, Diaz will probably just get a submission.
Diaz's supporters might note that his triathlon training will make him especially dangerous over five rounds, where he was never afforded more than three in the UFC.
All of these changes have some real merit, and could pay dividends in the UFC.
Even Diaz's skin has changed—he underwent facial surgery removing scar tissue and grinding down bone to make him less prone to cuts.
All of that said, Diaz's detractors will tell you a different story.
They will point out that he still gets hit hard and knocked down far too much. Zaromskis, Gomi and Daley all knocked Diaz down before Diaz recovered to win.
Daley in particular caused Diaz to face-plant into the mat before Diaz stormed back to stop Daley a minute later.
More than that, though, Diaz is still not very good at checking leg kicks. Santos was winning a lot of striking exchanges with leg kicks alone before he wound up getting submitted.
As for Diaz's improved BJJ, Diaz critics will point out that as good as Diaz may be on the mat, he's going to be fighting at a disadvantage against wrestlers in the UFC who are also very good BJJ practitioners.
Jon Fitch, for example, is a great wrestler and also a BJJ black belt.
After all, in MMA, when grappling occurs between two relative equals, the guy who gets the takedown usually wins.
The main problem with gauging Diaz's improvements over the past five years has been that he simply hasn't faced a high level of competition on a regular basis.
Will UFC 137 Reveal An Improved Nick Diaz?
Diaz's performance at UFC 137 against Penn should tell us a lot about how Diaz has improved in the past few years.
While Diaz's record of 25–7 (one no contest) might look better than Penn's 16–7–2 record, Penn has faced significantly tougher competition. Penn also owns the edge in common opponents, with wins over Sanchez and Sherk.
Although he is sometimes lacking when it comes to strategy and endurance, Penn is an extremely capable boxer with truly world-class BJJ and underrated wrestling.
If Diaz loses to Penn, it would be neither shocking, nor any real condemnation of Diaz's skill.
Penn is a great fighter.
Just holding his own against Penn would be as big an achievement as any of Diaz's wins over the past five years.
But if Diaz is able to beat Penn, especially in the early rounds when Penn is at his strongest, even Diaz's most ardent detractors will have to admit that he's become a much better fighter and is now a legitimate force in the UFC's welterweight division.