What the Bears are missing are a couple of guys that can move but also have the strength to hold their own against bigger nose tackle types. The whole OL are not going to pull on the same run play and having these guys that can move isn't as effective if the play gets blown up before they can use that mobility because the guys left behind can't hold their own.
So if Cody is pulling on a given play, is Daniels strong enough to stop the NT from pushing him too far back? What if Daniels is pulling? Can Cody hold down the fort? In the past you had two finesse guys in Long and Cody on the line but you also had Sitton, Long and Massie who were strong enough when all healthy to allow the finesse guys to work. Leno and Sitton were also fluid enough to pull from time to him.
Now you just have a bunch of mobile soft guys that get pushed around far too easily particularly with Massie being banged up as he is probably the only one left with above average NFL strength when healthy.