Mick was one of the oldest characters in the Rocky franchise, if not the oldest. But he was a good boxing mentor.

If I remember right, him and Rocky knew each other for a long time as Mick ran a boxing club and was the one who got Rocky a chance to be a sparring partner for Apollo Creed.

But Mick helps Rocky take things more seriously when Apollo Creed wants him as a actual opponent, not a sparring guy in training.

He was definitely very good and instrumental in Rocky’s two fights against Apollo Creed.

But his age and the stress of it all was too much for him when Rocky finally became the world championship boxer.

As he dies during Rocky’s horrible match against Clubber Lang. Dying pretty much the same time Rocky Balboa loses his title. Kind of sad, honestly.