Putting on the belt that’s attached to the bungee-like cord has become part of Dirk Nowitzki’s pre-practice routine. With strength coach Robert Hackett or equipment manager Al Whitley holding on to the other end of the cord, Nowitzki goes through a jumping program. He grabs the rim a set and slaps the glass a certain number of times. It’s not exactly a display of jaw-dropping athleticism. “I don’t work on it so I can go out there and dunk on people,” Nowitzki said. “I work on it to get my legs back under my jump shot.” It’s working.