Among other features of his game, Johnson clearly accented on defensive technique when so many others did not and he tuned it in to the given opposition. The mere possession of a basic jab put you ahead of a good measure of the field back then and Johnson not only had a jab but an excellent and fast jab at that.. Of course it's one thing to totally re-invent one's style but it's different prospect to further develop oneself from some fundamental platforms which Johnson did possess. At any rate, increasing mobility and output isn't stylistic reinvention or re-engineering per se. Johnson showed he could move and punch, so greater accent and allocation of energies in those departments would serve him better.
This should be the battle of da 2 Jacks, a far more intriguing and stylistic explosiveness battle. Surprised at all the Tunney support. I think it would take someone like Dempsey and not Tunney to unseat the first ever black ex heavyweight champeen.