How would it be a fluke? Do you know anything about Shogun Rua's career/fight history? Serious question.
well face, looking at recent history and quality of opponents, it appears that Machida is the superior fighter.
Rua's 4 year record is 6-2 will losses becoming more frequent later in his career.
He lost in the first round by TKO to Mark Coleman.
His next three victories came against an unknown savate-kickboxing artists and two people who were on losing streaks, I believe we like to call them tamato cans (Randelman and Nakamura) and even Overseem was a Tamato Can at that point (Overseem had an impressive start to his career, but had seemed to have lost it). Then he lost to Tyson Griffin.
He did get his revenge against Coleman, than beat Liddell, who is a greybeard on a losing streak. I would say his only credible win in the last 4 years came against Coleman.
Machida, on the other hand, is undifeated in his career, and has a 7-0 record in the last 4 years, with victories over the likes of Tito Ortiz,Thiago Silva (who was undefeated coming into that fight) and Rashad Evans (who held the divisional championship and was also undefeated coming in). Three strong fighters compared to the one that Rua had.
So the way I view it, the relevant records are
Machida 3-0 against Rua 1-2.
You can expect Machida to dominate.