Unsure of how he fits in, makes sense. Worried about his next contract would make sense too.
But hopefully he realizes what 25mpg on this team will do for him. Per-36 he was averaging career highs 18.3/7.2. Overall he's getting about the same number of shots he did as a starter playing 30+ mpg in Detroit.
Look at what happened to the perceived market value of Turner, Bradley, Thomas, and Crowder once they left Boston. If he or his agent are smart, they don't want to leave or get traded in 2019, they just want to make sure there's enough minutes to get that next payday.
And despite what the rotation will look like, there will be some injuries to give him more minutes. Not even talking about season ending injuries, last year Horford missed 10 games, Brown 12, Smart and Morris both28. Previous year Crowder missed 10, Horford 14, Bradley 27. Year before that Crowder missed 9, Olynyk 13, Smart 21. Minutes will open up somewhere.
But I can understand the reason for concern.