Former World No. 2 Tommy Haas, of Germany, and Mats Wilander, of Sweden, have said that Germany's top ranked player Alexander Zverev needs to improve considerably in order to become a contender at the Grand Slam tournaments.
According to RP online, Wilander, a winner of seven Grand Slam titles and a commentator for Eurosport, says, "For me, Sascha is currently not a candidate for a Grand Slam tournament title. Sascha is tactically not at the same level as compared to the top players.
He plays too passively and with little variation; and that is a big problem for the Grand Slams." Wilander also noted that Zverev has not done well in the best-of-five sets matches at the Grand Slams. "Five sets seem to be a big problem for Sascha.
He hasn't solved that yet. He has to understand that there are moments in five sets when you have to vary your game. Everyone has times bad phases during a long match, but you have to develop your strengths again. " Haas has said that the 22 year old pulls himself down.
"He pulls himself down. Boris Becker, John McEnroe and Novak Djokovic also had tantrums. But as a result, they raised themselves to a higher level and were even stronger afterwards. You can't see that with Zverev."
Zverev struggled at the recent ATP Cup when playing for Germany. He lost all three of his matches, the last two of them in straight sets and struggled heavily with his serve during his matches.