Gregory, a 6-foot-5, 243-pound pass-rusher who had 17.5 sacks in his two years at Nebraska, is the kind of versatile athlete -- he can rush the quarterback and drop into coverage -- that teams covet.
But marijuana is neither a new nor uncomplicated storyline in Gregory's life.
At the combine, executives from two NFL teams indicated to NFL Media that there were concerns about Gregory's Nebraska off-the-field "issues." And this was before Gregory's positive test from the combine came to light.
Gregory said he now believes he is "in a great spot," but getting there has been a process.
"I don't wake up every day saying, I'd really love to go smoke," he said. "It's not a struggle for me every day (now), it really isn't. In the past, hell yeah, it's been a struggle. It really has been. Now, I'm focused on my dream."
Gregory said he first smoked marijuana after graduating from Hamilton Southeastern High School in Fishers, Ind., and before enrolling at Arizona Western Community College in 2011. He had failed to qualify academically at Purdue, which represented a considerable disappointment to him, and Gregory said he turned to marijuana to cope with the anxiety.
He sat out the 2012 season with a broken leg but was still pursued by major colleges. In 2013 he transferred to Nebraska, where he officially tested positive for marijuana twice, in January 2014 and April 2014. (Gregory said Nebraska officials told him he would be kicked off the team if he were to fail a third test.)