The Detroit Lions will be without three of their draft picks when training camp opens on Friday. Cornerback Chris Greenwood and defensive end Ronnell Lewis have been placed on the PUP list, and wide receiver Ryan Broyles has been placed on the non-football injury list.
Greenwood is trying to come back from surgery he had to repair a torn muscle in his lower abdomen. He suffered the injury during OTAs in May, and his timetable to return is unclear. It's also unclear what kind of timetable Lewis is on. He took part in the Lions' minicamp in June, and the specifics of his injury are currently unknown.
As for Broyles, he is on the non-football injury list because he is still recovering from the torn ACL injury he suffered at Oklahoma. This is essentially the same thing as the PUP list; it just has a different designation because the injury didn't occur during a Lions football activity.
The important thing to remember is that these players can come off the PUP/NFI list at any time during the preseason. A couple years ago, Brandon Pettigrew spent all of one day on the PUP list. He was still recovering from a torn ACL injury, so perhaps this is more precautionary than anything and Broyles won't be on the NFI list for long.