I agree with you, but seeing as John Kavanagh has guided a fighter from Dublin to the pinnacle of the whole game and remained honest throughout, I put some stock in his views. I watched his recent interview with Ariel Helwani that you've quoted.
Personally disagree with his assessment of Nate Diaz. As you point out about Max Holloway, Conor McGregor has had issues with longer opponents posing equal or more reach. That's why he has had to scientifically develop his game since the first fight against Nate Diaz. Kavanagh openly views him as the biggest challenge of McGregor's career and states he's reasonably confident that no one will ever pose as big a threat to McGregor again.
Yet despite how difficult an opponent Nate has been for McGregor, he was light work for Dos Anjos and many others feel he would be light work for them too. Thing is if Dos Anjos fights McGregor now, I'd have McGregor as a huge favourite just because of how dominant he is with maintaining his reach. Dos Anjos has fallen well behind in the pecking order given his two defeats in a row to Alvarez and Ferguson though.
Khabib recently scoffed at the fact that we're talking about Nate Diaz at this level, who's lost so many times. He feels McGregor and the UFC brass are picking easier fights for Conor instead of giving opportunities to the "real contenders". It's somewhat hard to argue with that, despite how dominant Conor was on Saturday.
And on that fight, it must be said that Eddie Alvarez let down a huge number of MMA purists and sent McGregor's name so far out of proportion it's now going to be near impossible for anyone good enough to get a shot at him for the belts.
Its difficult to tell whether Nate Diaz would defeat the likes of Ferguson and Khabib, but they sure feel they would handle Diaz comfortably.
I think the overall reality is, when we're talking about opponents for McGregor, we're not talking about who the best fighters are overall. We're talking about who has the attributes to nullify McGregor's style the most to make it a close fight.
As great as Aldo, Khabib and Ferguson are, they have a huge task getting inside the reach without being absolutely caught clean with that counter left. Nate managed to do Conor for reach, durability and stamina. There are some doubts the remaining contenders can do the same, except perhaps Holloway.