Lopez admits he felt let down by the 29-year-old former Manchester City striker.
“In life, facts count, not words," he told Corriere della Sera.
“We are what we do, not what we say or write. There's only one truth here: the team have followed one path, Mario has followed another.
“I thought he could give so much, playing in the city of his birthplace. He had a lot to give but he had to do more, much more.
“These are the facts. Therefore, it's normal that there's disappointment. I spent a lot on him.
“He trained alone because his teammates chose to follow another path. It was optional, fair enough, but the group followed one path and he followed another.
“He didn't even show up on Zoom during quarantine. Even if he says he's feeling fit, he's not at the level of his teammates."