From Tekken Zaibatsu Wiki
Steve Fox had destroyed the research institute of the Mishima Zaibatsu, and finally settled a long-time feeling of resentment.
Steve was intent on returning to the world of the boxing again, but the majority of major boxing meets are canceled by the war that broke out all over the world. Steve, who knew no other trade than the boxing ring, had effectively lost his job and his passion, and went into depression.
Soon after, he received an invitation to train together with Marshall Law and Paul Phoenix. Steve, who liked the idea of training in a martial art other than boxing, accepted.