Tackles are average to above, solid, Daniels should be well along his learning curve and looked better as he got more reps. The off season should help Daniels and especially Long get their bodies into NFL condition. Long's best attribute last year was that he was hard to move due to his Buddha belly. He hasn't been able to train in the off season for years and I expect him to be renewed and refreshed this coming one. His 'might play T' days are over but he should still be able to play his spot at a high level if healthy.
I personally like Whitehair at C. He's good at all aspects other than shotgun snaps which is sorted well enough. If the Bear move Daniels there it will be due to snapping with the ball getting there faster and more consistently with a spiral. I like Daniels at G with our current roster. I'm sure Cody would be fine there as well but Daniels will become the better drive blocker. Both are good getting to the 2nd level but Cody has already shown to be VG at combo blocking, shading the G that needs more help and picking up defenders in space. That's important for a guy that often doesn't have a set assignment. He doesn't have that big anchor but extremely strong hands which is a life saver at the position.
I think going into this season counting on Long to contribute anything of value is a mistake, as evidenced by the past 3 seasons. Obviously, Pace disagrees with me, as they decided (and were limited by resources) to do very little to bolster the interior.
It's also possible we start to see a decline in Massie, as he'll be 30 entering the season.
Overall, I'd wager much of the same from this unit this season. Quite frankly, I'd be shocked to see a clear "improvement", and definitely don't 'expect' it.