Tekken 6 isn't going to be the worst selling Tekken when all is said and done, either. Here's the list of the best selling Tekken games
Tekken 3 - 6.91 million
Tekken 2 - 5.45 million
Tekken: Tag - 3.94 million
Tekken 5 - 3.66 million
Tekken 4 - 3.31 million
Tekken - 3.18 million
Tekken 6 - 3.16 million
Now, in the past 12 weeks, the Tekken 6 editions have sold the following:
Ps3 version: 60k
X360 version: 16k
PsP version: 7k
Sum: 73k
Now, considering that it has sold 73k in from week 72 to week 84, selling another 500k isn't out of the question. Another 200k is a certainty. In other words, Tekken 6 is looking to end up selling pretty much exactly as much as the average of the Playstation 2 Tekkens.
It hasn't really failed at all.