Relentless. Persistent. Resilient. Oklahoma overcame a six-run deficit Friday afternoon to advance to the Big 12 Tournament championship game on a Jackson Nicklauswalk-off two run home run. It will be the Sooners’ final athletic competition in a conference they’ve called home to for the last 29 years following the come-from-behind 8-6 victory against Kansas. “Our pitching staff came in there and pitched their guts off. Grant (Stevens) came in there and pitched with his heart on his sleeve. I just wanted to do something. You never want to try to hit home runs, but I was just trying to compete a…