Smith played all season long in 2017, so it was 20 months from his injury when he was considered healthy enough to start an NFL game at linebacker. "Full potential" is a bit subjective, he obviously wasn't the same player he was a year later, but he played full-time at a position that requires quite a bit of changing direction, reacting instead of dictating where you are going, etc.
JR got hurt 23 months ago and it just seems like he still has a ways to go to be able to play. Hopefully I'm wrong.
Yes, he played, but Jaylen Smith was clearly hobbled in 2017.