Ken Burns Theory
Ken Burns Theory
[Cueball is standing next to Megan.] Cueball: Lincoln was "President" in The Civil War (1990), the same office held by Johnson in The Vietnam War (2017). Cueball: And Baseball (1994) briefly showed 1960s "protesters." I think they were protesting Johnson's war! Cueball: It all fits!
[Caption below the panel:] I have a fan theory that every Ken Burns miniseries exists within a single cohesive universe.

Some fiction writers and filmmakers set some (or all) of their works in a common, or shared, universe , meaning that characters in one work can conceivably meet characters in another work via conventional travel. Often, it's unmentioned or even outright denied that two distinct works take place in the same universe, but nevertheless  fans may try to find a way to relate them to a common storyline (such as the examples of fan theories described in this Mental Floss article ).
Ken Burns is an American filmmaker renowned for his historical documentaries; thus, all his documentary series are set in a common universe - namely, the real one - and usually the setting is a small part of that (real) universe: the United States in the last two centuries. The series mentioned are
The joke here is that Cueball is trying to find the common features between Ken Burns' series to set them in a common universe, as a fiction fan would do, "discovering" similarities between series that are simply facts in American history. For example, several series have an office named "President", which Cueball "guesses" to be the same for Lincoln and Johnson , and which obviously is just the President of the United States . Cueball has also drawn inferences from facts established in one series to draw conclusions about another, when he ( correctly ) concludes that the 1960s protesters depicted in Baseball were protesting "Johnson's war" as depicted in The Vietnam War .
The title text continues the joke by saying these stories are set in the "KBCU", an acronym which stands for "Ken Burns Cinematic Universe" similar to the popular Marvel Cinematic Universe (MCU).
Doris Kearns Goodwin , mentioned in the title text, is a famous historian who has written biographies of several U.S. Presidents. She is also a fan of baseball's Boston Red Sox and a sportswriter who appeared in the Baseball miniseries. Cueball states that having a character that had written biographies of both presidents, while also a sportswriter was "unrealistic". It's not uncommon for writers trying to fit different stories into a single 'universe' to cause a single character to become important in both, even though it makes little narrative sense. This can be denounced as "trying too hard" to fit the stories together.
Finding that certain aspects of reality seems unrealistic is quite common . This is because our judgment of realism is based on our own experiences and our (often flawed) perception of probabilities.  Because the complexities of the world generally exceed any person's experience, and because it's natural for highly unlikely events to occur sometimes, real events can seem implausible. In this case, people tend to think of sports journalism and political biography as being very different fields. The odds that one person would do work in both fields important enough to be relevant to all three documentaries under discussion feels unlikely. As a result, we (or rather, Cueball) deem it as unrealistic, even though it actually happened.
[Cueball is standing next to Megan.] Cueball: Lincoln was "President" in The Civil War (1990), the same office held by Johnson in The Vietnam War (2017). Cueball: And Baseball (1994) briefly showed 1960s "protesters." I think they were protesting Johnson's war! Cueball: It all fits!
[Caption below the panel:] I have a fan theory that every Ken Burns miniseries exists within a single cohesive universe.
