Sheldon Richardson is on his third NFL team just five years removed from being drafted 13th overall. After moving on from Sharrif Floyd, the Vikings' own first-round pick who suffered what could be a career-ending knee injury during surgery, the Vikings incur a different risk in Richardson.

Richardson was suspended four games before the 2015 season for violating the league's substance abuse policy after testing positive for marijuana. He was then suspended one game for the 2016 season for violating the league's personal conduct policy.

"We did a lot of research on that," General Manager Rick Spielman said of Richardson's off-field issues. "That was maybe 2½, three years ago. We talked to a ton of people about it. We did, as we always do, as thorough of a job as we can. And after spending almost two days with him, felt very confident that him coming into this culture, into our locker room, that he'll fit right in."