I don't understand where you come up with the idea he was one of the worst players on the roster last season. Was he great? No, but he provided a steady veteran presence who could create for himself and others. He averaged more assists per game than everyone except Booker and Tyler Johnson and his assist to turnover ratio was better than any of the plug and play PG's like Okobo, Melton, Canaan, or Jawun Evans. His FG% was down some but he was playing out of position as a PG, which is something he hadn't done for over a decade. Unlike the last few years, he didn't share the court with any offensive threats other than Booker so opposing defenses were able to contest his shots more and apply more pressure overall than he had to deal with in some time.
He would have been a better fit on this years roster and would have played to his strengths more as a bench scorer. Yes, he can be a chucker but no more than Tyler Johnson was before he got glued to the bench. I'd much rather have Crawford forcing offense than Tyler. Ideally there would be someone else who came off the bench who could create for themselves and others but that was a gaping hole in the 2nd unit all year.
Plus he showed he's a solid veteran leader while here, much more than some guys who were paid specifically to be veteran leaders like Chandler, Dudley, and Ariza. He's also more productive than those guys, still.