If you also want debates to be fruitful, you could stop building strawmen, and misrepresenting arguments so that you can dismiss them for what they didn't in fact say - as you have just done with your false summary of my arguments about Nadal.
Tennis, unlike a sport such as running, is a sport of relative and not absolute achievement; it can't be measured by time over distance, for instance. It has to be assessed by performance in relation to an opponent - and also against how the game has been played over the history of the sport, taking into account changes in technology as well as technique, training and playing styles. It cannot be measured simply by results.
Added to that, we have had sports and antidoping officials state that the game has a doping problem - that Spanish sport also has a doping problem - and that tennis is amongst the top 4 sports in that regard, which suggests that some of the most successful players could well be doping. If that is so, we should expect to be able to literally see it, in front of us, on the court. Doping will make a difference. For much of his career Nadal in particular has been the subject of open conjecture and even accusations (although these have not been proven by a known failed drug test).
My view that the latest French opened final showed likely doping is informed by that context and is based on Nadal's level of performance in relation to the quality of his opponent. It isn't sufficient to say that Djokovic's defeat was only attributable to his relatively poor play - of his having a "bad day" - as he could not match or even come close to Nadal in any part of his game; he didn't have the same court speed, power, accuracy or consistency. He couldn't play better because Nadal's level of play wouldn't allow it. If Nadal's opponent wasn't a player ranked in the top 100 I could have accepted much of what I was seeing, but Djokovic is one of the greatest players of all time, who has dominated Nadal for the better part of a decade, often beaten him on clay - including at the French Open - and yet stood no chance. I have never seen him lose to another player 0-6, 2-6, as he did to Nadal in the first 2 sets.
Over more than 15 years, I doubt I have seen Nadal play at such a high level, yet he is now in his mid-thirties. I have often seen him struggle with apparent injuries in the past, even taking months off, and many have pronounced his career was over. Yet he invariably comes off injury stronger than before - unlike any other sportsman I have seen. His disproportionate dominance on clay is because he is far stronger, faster and more durable than any other tennis player - and not just today but in the history of the sport. Yet I have also observed how his career has followed distinct cycles of performance, when in the later part of each year he is nowhere near his best level that typically peaks at the French Open.
But aside from his incredible fitness, his skills as a player are not equivalent to Federer and Djokovic, who have 19 and 16 off-clay majors respectively to Nadal's 7. As I have said, his clay dominance is achieved by an overwhelming physical superiority. He is a heavyweight to everyone else's middleweight - in a sport of the finest margins. What else might that be attributed to except doping, in a sport with doping issues?
In any discussion of doping I have never known you to have accepted that any named athlete has doped, unless they have incurred a confirmed doping violation. Even with such a violation you haven't accepted that they would have benefited from doping. You have only conceded that doping exists as a practice, but that no one appears to be guilty of it. You don't accept arguments that doping confers performance enhancing benefits, but say only that there is a "belief" that it does.
There is no way I am going to be able to persuade you that a top tennis player in a sport that has been identified as having a doping problem is a likely doper - and has benefited from it. Unless there is a confirmed violation and you know what it was they took you dismiss any other argument as "magic". In your world, the tip that we can see is the whole iceberg.