That's like saying because the Rebels beat the Cru this year that they are the better team.
Also it was an upset - go look at the betting odds before the game. The Sharks played their best game of the year and the Reds had some bad luck with a key injury, a poor substitution and not playing their best game. It happens
The Rebels are a great example of a team making progress they only really got spanked by the Cane's this year but were competitive against the Stormers in Cape Town in their last game of the year despite being without their two marquee players. What this goes to show is that any team can turn up on their day and win.
BTW The team that wins the competition will deserve to win it. If your team has been eliminated they weren't good enough.