1) Smart can guard 3 positions , not 1 and a half like Bradley(the half being smaller SG's), Smart is also a much more versatile player on offense . He can finish at the rim unlike Bradley, He has PG and Play making skills unlike Bradley, and can give Rondo some rest .
2) Rondo isn't going to get a good return in any trade this year , or maybe ever. He is much more valuable to the C's than other teams who would be trading for him , and is still a top 20 player
3) If we let Bradley Walk , there is a good chance we would have enough cap room to re-sign Rondo and still have enough money to add another Max free agent ( Love or Gasol) next year
4) If Rondo is gone we completely take ourselves out of any chance at landing a big time free agent , taking away avenues for management to go down . By keeping Rondo we have so many more options . Trading him for peanuts doesn't do anything for us .
I think Bradley is a goner