We have several here on the forum which expertise either surpasses or fully matches that of your named experts.
Can you prove that those several users are tennis experts? Pay attention: the only way you can prove it to people who are not
tennis experts is to provide reliable source which shows that they are recognized as tennis experts.
The main difference between paid experts and non-paid experts is that the former have a larger incentive in keeping public interest. They will always be better served by overhyping than underhyping. As I am sure you have seen examples of in the past. If not, try to search for expert opinions about the future career of Donald Young about eight years ago. If Djokovic in the future underperform comparatively as much as Young, in relation to expert opinions, then he'll never reach another slam SF.
Do you claim that Flink and Sampras said what they do not
Flink was wrong about Nadal. Surpassing Federer?
He is a bandwagoner. His prediction about Djokovic was before he lost at RG, Wimbledon and USO.
Sampras predicting Federer winning 10 Wimbledons... Roger might not even win an eighth.
You have not
answered these questions:
1. Can you tell me which tennis expert is always
2. Can you find tennis experts who said that Djokovic will not
reach double digits?