The team announced the No. 7 overall pick is dealing with a mild disc herniation in his lower back. Williams will be held out of organized team activities this week and miss next week's minicamp, which concludes offseason workouts.
Two weeks ago, coach Anthony Lynn expressed concerns the rookie could fall behind the developmental curve.
"I'd like to see him out there next week because he's getting behind right now, and we've got to get him back out on the field," Lynn said in May. "If he wasn't a rookie it would be different. But he has so much to learn, and some of this you can only learn on the field."
Williams could be a candidate to begin training camp on the physically unable to perform list if he's not fully healed by late July.
The offseason injury puts the rookie behind schedule and might hinder his 2017 production. Williams could end up opening the season behind Tyrell Williams and Dontrelle Inman in a deep L.A. receiving corps.