Well Djoker is the ONLY player among Fed, Nadal and Murray that held 4 consecutive GS AT THE SAME, 2015 WB, US and 2016 AO and FO. That has not been done since Rod Laver in men tennis. Even your GOAT Fed could NOT. Take that.
As far as Zverev is concern, until Zverev wins GS, he just needs to shut up. Winning Master 1000 and YEC, while it is a big achievement, it is NOT GS.
In a GS event, you have to win 3 out of 5 sets in a two weeks time frame. That's why GS is so much more difficult. That's why Zeverev best performance at GS was the QF at the 2018 FO and he was pushed to 5 sets in round of 2nd, 3rd and 4th round. Thiem just totally destroyed in the QF. At 2018 Wimbledon, Fritz pushed him to five sets in the 2nd round and then Gulbis finished off Zeverev in the fifth set 6-0 in the 3rd round. Do you see a pattern here? Even Coric beat Zeverev at the US open in 2017.
Until Zeverev makes it to the final of GS and win it, he just needs to shut up. He has not achieved anything yet.