MINNEAPOLIS — The little glimpses of potential greatness are so tantalizing. They demonstrate the talent J.J. McCarthy possesses — the same traits that made him a top-10 pick just two years ago. McCarthy evaded pressure in the first quarter of Saturday’s preseason bout with Baltimore, stepped up and launched a 50-50 ball that Tai Felton ripped down from the sky for a 50-yard gain to move Minnesota into the red zone. “I thought that was a really …