I agree entirely with TVLurker that the lack of consistent talent has hurt CBS News. Constant reimagining, rebranding, and relaunching morning and evening news products has been a disastrous approach. Why CBS blows up and relaunches "a new era" every few years, NBC and ABC make tweaks to evolve their shows. However, I think the 1995 affiliation switch gets overplayed. Indeed, it mattered then and in the immediate years that followed. But CBS primetime was able to ascend to the top of the network pile. Same for daytime. I believe the problem with CBS News is CBS News. The culture was set during Cronkite and never changed.
There's no doubt that CBS News has an excellent pedigree. But NBC wasn't exactly asleep at the switch in the early days with Huntly and Brinkly, plus the Today Show. NBC News has continued to evolve as its audience has evolved. Heck, the early days of ABC News were a non-factor on the national stage. It wasn't until Roone Arledge envisioned newscasters as "stars" that they started to gain traction. In the 1980s and 1990s, NBC and ABC invested in their on-air presentation, including sets, music, graphics, etc.. Television is, after all, a visual medium.
Meanwhile, the culture of CBS News seems perpetually stuck in the Cronkite days. "We don't need to invest in our on-air presentation because we are CBS. Walter Cronkite worked here, damnit! Our reporting is the star." That worked in the 50s, 60s, and 70s when the picture quality was poor and Americans had two or three choices for news.
And when CBS does invest, it doesn't feel like they are being innovative. They seem to deploy technology as a means to cut costs. Take a look at the green screen studios they are installing at their local stations. To me, this is just a way to cut the costs of building physical sets. Other people are using these types of sets, but they are usually employed as a next-level storytelling tool. CBS is putting entire newscasts into a virtual environment, which doesn't seem to serve any purpose other than to say "we are the first to have a virtual studio!" By the way, WCBS was the first to have a virtual studio. See what good it did them. They had it in the late 90s. If you don't remember, look it up. It was over-the-top ugly.