Having Zoro spend two years training under Mihawk ultimately ruined Zoro's character.
Pre Timeskip his goal to be the best Swordsman was the reason Zoro constantly pushed himself to his limits. But there were also things and enemies that he couldn't beat and had to get himself stronger.
After the Timeskip he doesn't anymore. The two years training under Mihawk ties his strength to Mihawk's more than any other character. So if he had to struggle or isn't able to beat a foe or cut something then it reflects onto Mihawk.
Since the Timeskip Zoro hasn't pushed himself like he used to because the only goal for him left is to beat Mihawk. Not cutting diamonds, or beating anyone else it's only Mihawk.
Take Dressrosa, when it came to the Birdcage Zoro didn't try and cut it. Because if he couldn't it would look bad, instead of something he would need to get stronger to do.
Pre Timeskip his goal to be the best Swordsman was the reason Zoro constantly pushed himself to his limits. But there were also things and enemies that he couldn't beat and had to get himself stronger.
After the Timeskip he doesn't anymore. The two years training under Mihawk ties his strength to Mihawk's more than any other character. So if he had to struggle or isn't able to beat a foe or cut something then it reflects onto Mihawk.
Since the Timeskip Zoro hasn't pushed himself like he used to because the only goal for him left is to beat Mihawk. Not cutting diamonds, or beating anyone else it's only Mihawk.
Take Dressrosa, when it came to the Birdcage Zoro didn't try and cut it. Because if he couldn't it would look bad, instead of something he would need to get stronger to do.