He just wasn't destined to be a professional boxer. Its not for everybody and it takes a lot of mental toughness, that he just doesn't have. Not in that capacity. Over 99% of people don't possess this mental toughness, so its nothing to be ashamed of. He does, however, seem to have a good boxing brain. He has continued with the great Emanuel Steward's approach and does have the experience of being a fighter himself, which is valuable. I really hope he sticks with the training side of it, because he seems to work well with fighters and can still do big things in the sport.
Great trainer I think is quite a stretch, I find him quite unremarkable and only in his current position based on his relationship to Steward. That said, he's infinitely better than Chris Algieri's trainer.