The O line combo that solidified later in the season was Leno, Whitehair, Mustipher, Bars and Ifedi. They actually got the run game going a bit which allowed the team to throw off play action more often and move Trubisky around. Olin Kreutz has talked about how Mustipher did a great job in the middle there which allowed Whitehair to move back to guard where his game picked up.
We go into this year with improvements on two of those 5 positions, presumably Jenkins at LT and Daniels back at RG with Ifedi at RT. We got help on our O line. Ideally we'd be able to put Ifedi on the bench in favor of a better RT but we substantially improved through adding Jenkins/Daniels while Bars got some valuable experience as the primary backup. It could be worse.
All this "oh noes the O line is awful therefore I can't play my new QB" is nonsense. Players play, that's what they're called "players." I highly doubt Justin Fields would say "yea nah sorry can't play behind this offensive line" so why should we?
That was under a totally different OC. The team is going back to Nagy who has never called a good offensive game.