As we have been seeing most perform well at the start of the year but they fade away at the end and some perform poor at the start and come good at the back end of the year like we saw with Medvedev last year. We can see the talent they all have, they just need to be able to win against the top three in grand slam finals. Like I said anyone can go back and see that I'm a big fan of Thiem, I've even had several bets on him to win the French Open for the last 2 years before it started because I believe he will be the next great clay court player once Nadal retires.
agree for Thiem, think that he will be great on clay, and he would be now, if there is no Nadal, what is the issue there is that Thiem is also not getting any younger, and he is not a talent anymore, in his age Nadal was already crowned "clay king"
regarding Medvedev and other players, IMO, Nadal, Federer and Djokovic are not that great, it is more that competition is really bad, so these three shine out, just look at some side-players that hanged out in top 10 for several years, without being called great, for example Berdych, Tsonga, Del-Porto, would you call them great as well, and some of them even managed to win grand-slams when top 3 where at their best