By Daniel Bates The Cowboys retained a huge piece to their 2021 turnaround in defensive coordinator Dan Quinn. After riding the coaching carousel, Quinn came to the conclusion that there’s unfinished business in Dallas. “I want to be right where my feet are,” Quinn told Cowboy Maven. “But that doesn’t mean I’ve always been fully happy where my feet are. I’m happy here.” “I have unfinished business here,” the 51-year-old coach continued. “We have the right people in place to accomplish the things everyone in this building is working to accomplish. We’re doing that right now. We’re doing it toda…