Bill Goldberg is still big. And quick. His hands are fast, and when training in Muay Thai kickboxing, his discipline of choice for a workout, he still very much looks like he could kick your ass, even at 58. During a Saturday-afternoon training session at Black Diamond Martial Arts, just a few miles from his home in Boerne, the WWE Hall of Famer sweats through several rounds of a high-intensity striking workout with his trainer, Casey Johnson, who handles the pads and instructs him in combinations. Johnson calls out numbers, and Goldberg strikes in the corresponding locations—up high, down low—the same sequence of moves he pantomimed when he emerged from sparks and smoke just a few days earlier on Monday Night Raw. On that occasion, he…