"He's doing a good job in his rehab," O'Brien told NFL Network's "Good Morning Football." "I think he's on schedule to be able to participate in training camp. We're excited about that."
In March, O'Brien told reporters that Watson was "ahead of schedule, but there's still a lot of work."
Watson tore his ACL in practice in November. He said last month that he was taking it one day at a time and didn't know to what extent he would be able to participate in the team's offseason training program.
Information from ESPN's Sarah Barshop was used in this report.