Talk Tennis Guru
He obviously didn't blossom earlier if he can't make it to a QF of one Slam the entire year.Federer wasn't having Z's success at 20 so it was more understandable for him to struggle. Zverev blossomed earlier.
I mean when you are world no.3, slam contention should be expected from you.
I just explained that. Do you honestly think he would be world #3 in 2011-2013? He's be lucky to be top 8.