I'm no fan of Zverev and Lendl is definitely accomplished but since Ivan came on board, Zverev has just fallen off completely. Bit rich to say that Lendl coached Zverev to his only major title at the WTF when Zverev had won 3 Masters titles before he came along.
Maybe there was something to it when Zverev said Lendl just talks about golf and that.
Zverev hired Lendl in late August 2018. His results after:
3R US Open loss to Kohlschreiber
2 Laver cup wins over Anderson & Isner
3R Beijing loss to Jaziri
SF Shanghai loss to Djokovic
SF Basel loss to Copil
QF Paris loss to Khachanov
And then of course the WTF beating Cilic, Isner, Fed and Djokovic to win the title.
And then his 2019 hasn't been the best with just 1 ATP250 title.
Besides the 2018 WTF and Laver Cup, he's had 0 top 10 wins. None in 2019.