"I can tell you about Koeman from my personal experience, and I have very little to tell you about Koeman," he said on Cataluyna Radio.
"He provided me absolutely nothing.
"I wasn't happy, I asked to leave and I went to Milan.
"We'll see how he does at the Camp Nou."
Barcelona are going through a crisis, yet Deulofeu didn't seem too bothered.
"The truth is that Barcelona's [situation] does not bother me," he said.
"In fact, right now, I don't care."