By Andrew Holleran Dak Prescott had to spend most of last offseason rehabbing from his serious leg injury suffered against the New York Giants in 2020. This offseason is different. Prescott explained to reporters that he’s now able to work on everything this offseason, including his foot speed. “I’m not rehabbing one thing. I’m working on my whole body,” he said. “From my foot speed, it’s not just putting this down. Now it’s, ‘Can I get this thing faster than they’ve ever been?’ It’s about improving on the person and player I was before the injury now and being the best player I can be for thi…