This shows that you didn't read at all, do you? He was winning some points with Hyakuren and Saiki until Yips kick in. And due to Yips old explanation in the old PoT, if Echizen is winning in the beginning, Yips shouldn't kick in at all. That would required new yips.
...so?
You can't change what already happenned, so either the new explanation that everyone is following is wrong, or Konomi contradicted himself talking about one of the most important characters (and that, would suck). I won't keep talking about this though, it's way offtopic.
About the rest of the things... I disagree with so many that I dunno where to start.
We don't know if Ryoma uses PoP whenever he wants to. In fact, we know that even if you unlocked it before, if you don't "really have fun" you won't use it again. It's not like any other Muga door. At least, that was what Nanjiroh said (and when Fuji talks about Oni's TnK, he says the same
http://www.mangareader.net/new-prince-of-tennis/99/14 ). If it had been used (as it's such an important Aura in the PoT world) it would had been mentioned. Gyro, and every single thing you named after that are just normal techs... why would he forget how to give a spin with his arm? It isn't the same as an Aura, at all.
The fact that the PPs give Ryoma TnK doesn't mean anything. The PPs give Kirihara Muga! but we haven't seen him use it since Kanto.
Now, back to topic, you're being unfair to Duke. He's the freaking No.3 . You're saying that Irie, Tokugawa, Oni, Ryoga, Yamato and Marui are clear exceptions to the rank = power rule (I believe that 6 exceptions are enough to say that a rule is wrong, but wtv)... but that doesn't mean that Duke is another exception. You like it or not, he's 1 rank above a guy that can hit the Aura shot (thank you Kaoz), the same shot that could have killed Tokugawa. Is it to hard to assume that Duke can return the Aura shot? If he is able to, then he's clearly better than Tokugawa.
Also, come on man, "foolishly"? "stupidity"? "I don't know why I'm arguing..."? Chill, we're discussing a manga, don't take it personal