Robin was spot on at that time, it was a training session right before the only possible match where we could still qualify for Euro 2016, with Memphis having 0 goals and 0 assists during the whole qualifiers and fannying about, playing backheels when he should've just laid it off. In a recent interview he explained they weren't angry anymore though, and way too much was made out of such a small incident that happens on a weekly basis at every club.
Memphis can't help it that he's just not good enough, his footballing brain was his biggest flaw at PSV too, he just doesn't 'see' it. He has excellent goalscoring instincts though, if he chooses the right club he might become a decent player around the 25-28 years of age mark. His ego makes him very unlikeable, but he might become a little bit more humble when he's older too.