I live in Chicago and subscribe to the Sunday edition. I also read the digital edition, and have found it lacking, particularly since inauguration. In recent months Michael Ferro became the majority shareholder in the Tribune, a person obsessed with celebrities and not so much in local or even national news coverage. He's the guy that fired all the Sun Times photojournalists and mandated reporters use their iPhones instead.
The paper has struggled to find its place in trying to be like the NY Times or Washington Post, covering important national issues, but without the same resources. Meanwhile, hyperlocal sites like DNAinfo have filled the niche, which has strong FB engagement because it provides content people are interested in, but the Tribune isn't providing.
Instead of blaming a third party which bears no obligation to send traffic, the Tribune would be better served in providing better local news coverage and less in areas which aren't compelling (celebrity gossip) or where it can't compete (national coverage like NYT).