Getty Quarterback J.J. McCarthy of the Minnesota Vikings. Minnesota Vikings quarterback J.J. McCarthy hasn’t been overly sharp early on this preseason, which should be cause for concern throughout the organization. Struggles in June for a 22-year-old entering his second NFL season aren’t uncommon — particularly in McCarthy’s case after missing his entire rookie campaign with an injury. But difficulties against one’s own team in practice, which McCarthy suffered last week by throwing at least