If Ainge feels confident that he can develop Jaren Jackson Jr into the next Bosh, or Wendell Carter Jr into the next Horford, then it's very rational to consider trading Rozier when you factor in the young players on our bench, the draft picks we can't roster, and other considerations.
Others like Bamba and I see potential, but his poor passing and 3pt shooting concerns me. Carter had 13-9 and 2+ assists and blocks a game on 41% 3pt % on low volume, he at 19 reminds me of a 20 or 21 year old Horford.
Jackson had 3+ blocks per game and 1+ assist per game in limited minutes, had 15-10 per 36 mins, and seems to do everything at 6'11" from post up to shoot 3's off the dribble to drive in from the 3 point line for a dunk. He's more raw than Carter, but could become a mini Embiid.