Personally I think free throw shooting should be Rondo's biggest priority when talking about improving his game.
The next part would be deciding how important shooting jumpers and earning the respect of the defender and extending the defense at times is.
Which option would be best:
1. Who cares about outside jump shots. The space he gets, he uses to penetrate and have space to pass.
2. Working on the jumpshot is important and he needs to use it and improve.
3. If he's giving this much space, why not have Rondo work on shooting three pointers. Focusing on threes over a 12-15 footer would be better since it would extend the defense even more and if Rondo gets by his man for playing him too close he'll still have more room to pass or drive since his defender is behind him.