This.
Jennings has the makings of an Iverson (for the good as well as for the bad) 'Reke has the makings of a Billups 2.0 (never saw Frazier play) Flynn has the makings of an Isiah, and Rubio, IMO has the potential to become something altogether more special, but he hasn't progressed at all in the past two years and as Dylan Moran said, potential is like your bank balance, there's always less then you thought.
Aside from that, from what I saw of him in Rome last season, he doesn't do nearly as well in a structured offence as he does when he's simply allowed to take the ball and go to work.
All thinks considered, I think the Kings made the right decision.