The OP has a few good points, but forgets the fact that there is a salary cap to contend with.
A "big" upgrade at OT is a very expensive option. I think a quality Guard would be cheaper and would provide a lot of help to the run game. The RBs are not holding the run game back, the blocking is.
CB another expensive add. Pass defense has be great in the back end. Keep what we have and use the draft to add help.
Star may be over paid, but with 7.7 million in dead money against his 9.2 million cap hit makes him a keeper imo.