We have already discussed this to death (poor old dead horse and all that). Slower courts = more physical tennis = longer time needed for players to grow into their prime. One young player to buck the trend? JMP and guess what he is a beast of a man! Look for people like Dimitrov to really turn it on at 24-25 when he has the physical strength to dictate play for the full duration of a match (currently he often flickers out after a strong first set).
Luke had a better H2H but Vader is still the GOAT.