Despite that he hasn't won any silverware since then; he sees their split as being due to differences that they've had for some time and that they sat down at the US Open and came to that resolution.
He also saw his work with Maria Sharapova as being the main issue with Coric not being given the attention as a result.
“There have been differences for some time, since the beginning of the year.” Coric said earlier this week to MSN.
“They reached the pinnacle at the US Open, after which we all sat around a table and decided to interrupt the collaboration.”
“We can say that, it certainly did not help to resolve the differences and made the situation worse.” He commented on Piatti’s work with Sharapova.
“This was one of the main reasons. He is following several projects and could no longer focus fully on me. Given this and the previous divergences, we assessed that the separation was the best option.” Coric added.
https://twitter.com/RPiatti/status/1168986415058886658?s=20