"Joey is one of the easiest people to manage and handle but Joey's biggest problem is managing himself," Kay said.
Related ArticlesShearer says Boro clash will decide fateBarton let everyone down, says ShearerIt's all about not losingShearer: Career in picsGive Joey Barton a break or Premier League circus will just make him worseDavid Cameron praises Baroness Thatcher and vows to emulate her as PM"He needs support and he gets it and he needs to maintain that. He is no harder to teach than any other players I have worked with. In fact he is easy to teach. He listens intently.
"He is an intelligent man. That sounds rather preposterous but I stand by that. To manage him is not hard but as well as the physical training he needs the other type training to grow up. This is his time and he knows that. He needs to grow up.
Kay continued: "He has made tremendous progress and continues to do so. That's one of the reasons he's so mortified with himself because he knows he has let everyone else and himself down.
"A lot of things have been happening. But it's like anything else happening in our work. It's no use someone attending us for a week or two and then just going away and doing nothing. You have to maintain it. Recently he would be the first to admit that his maintenance of his well being apart from on the training ground has not been up to scratch.
"But he hasn't gone out and got drunk or anything like that. He has made a rash tackle and the consequences and ramifications are terrible. It might sound strange but I'm proud of what he is doing and the changes he is making in his personal life. He has come on leaps and bounds but that sounds preposterous when you see what happened on Sunday."
Barton's career has been punctuated with misdemeanours off the field and he was sentenced to a six-month jail term last year for assault and affray in Liverpool city centre before being handed a similar punishment for his training ground attack on team-mate Ousmane Dabo during his days at Manchester City.
He incurred the wrath of interim manager Shearer after being ruled out of the rest of relegation-threatened Newcastle's season when he was sent off for a crude challenge on Xabi Alonso during the 3-0 defeat at Liverpool last weekend.
Kay added: "Joey doesn't need to explain what happened. He's mortified. No other player would have made that tackle and Joey himself can't believe he did it. That's' the story of Joey.
"Let's put it into perspective. It was a tackle. It wasn't malicious whatever anyone might think. I know it didn't look pretty. It was just ill-judged, ill-timed. Rash, impetuous, all those things.
"How many chances does Joey need? No one can punish Joey more than he is punishing himself at the moment. He's mortified. He has apologised to the manager and the players and the fans but apologies are shallow. There are ramifications to things you do and he has the consequences happening now.
"Joey would love to work with Alan Shearer. He has enjoyed immensely the time he has been there. He feels very much that he owes and the club and the fans. He has played a handful of games some of it self-inflicted and some of it because of the injury to his metatarsal."