NORMAN — With two weeks left in the regular season, Oklahoma appears to be safely in the NCAA Tournament field. But as far as the Sooners’ regional hosting chances, the margin for error is razor-thin. OU (30-16 overall, 12-12 SEC) has lost back-to-back series. The Sooners lost two games of three at home against Florida last week after going 1-2 against Auburn in the previous series. “I think the biggest thing that we have to continue to do is continue to attack,” OU coach Skip Johnson said on 107.7 FM The Franchise. “I think we’ve lost that edge to attack — offensively, defensively and on the mound. You lose confidence when that happens.” At No. 24 in D1Baseball’s latest poll and No. 19 in the RPI, Oklahoma still has an outside shot at hosting the regional round of the tourney — but it feels like the Sooners must win both of their final two series to have a chance. And that starts on Friday against No. 17 Arkansas. The Razorbacks’ (32-17, 13-11) conference slate has been similarly up-and-down.…