They upgraded the OL and got a serviceable CB.
You will never go wrong getting better at OL and they likely have three guys who are Pro Bowl candidates as starters (Jenkins, Banks, and Zach Tom). Walker is a decent LT and between Rhyan and Walker they should get a serviceable RG. That should have a strong unit.
Now, they need to do something in free agency or in the draft to upgrade their edge rusher position and WR. Gary is fine. You'd like him to be more of a playmaker, but he's above average. Van Ness has not good and there is no way to sugarcoat that. If he doesn't improve, that limits the ceiling of that defense no matter who is playing DB.