On a crisp Monday afternoon, the helmet of cornerback Lorenzo Doss sat alone in the grass.
Minutes earlier, a long airhorn blast had signaled the end of Carolina Panthers minicamp. Players and coaches filtered off. But the No. 31 helmet stayed, because its owner was busy.
On the middle field, Doss lined up inches away from wide receiver Austin Duke. With backup quarterback Garrett Gilbert throwing, Doss covered Duke as he ran slants and stop-and-goes. Then he found an assistant coach willing to serve as a ball carrier, and worked on forcing fumbles from behind.