Tldr: it’s post-modernism because all this discussion of culture and the emotional journey is designed to move away from wins and losses, since these are absolute definitions, and in post-modernism you cannot have absolutes. (I’m putting this at the top to change it up)
What you’re defining as post-modernism is closer to what modernism actually is which was a complete termination of classical culture following WW1, where society looked upon the great traditions that came before and realized they ultimately failed and were meaningless, because how could such a culture exist and yet still lead to such a war. That’s why after WW1 there’s such an immediate and absolute break with ‘classical’ tradition, and everything after that is modern. The phrase The Great Depression is ironic in this sense, since it was both physical and cultural. For example, look at 100 year-old novels like The Sun Also Rises or The Great Gatsby which are so modern and relevant to our exact moment in time. Or look at the music of Igor Stravinsky and how he broke with the conventions of classical music right at the outset of WW1.
Post-modernism is a continued development of modernism where that now since there is no culture in place, we have to each struggle alone to somehow mash together a new culture out of this madness. Unfortunately what we’ve developed most out of this is the egotistical concept that “you have no right to tell me I’m wrong since this is my experience and it’s true for me.” For better or worse, that’s become the most derided concept of what post-modernism is. But that’s why whatever you believe becomes the truth and therefore there can actually be numerous truths to reality. That’s why a single paint-stroke across a canvas can be so fakely meaningful, because it has such compelling meaning to the painter even though it holds no true value to society as a whole.
Other examples in society are the childish idea that everyone is a winner and everyone gets a medal just for participating. We readily implant our children with these worthless ideals, or even the ability to down-vote on Reddit where you can just hide away the replies that aren’t true enough for you, or Yahoo Answers where you can select the worst possible reply as being Correct. Or some people still say Pluto is a planet, and thus depending on who you talk to there are either 8 or 9 planets (and even more if you believe Ceres should be a planet, or Planet X or Niburu, etc.)
And thus, therefore, in conclusion that’s why in my post I stated it’s post-modernism because this discussion about culture and the emotional journey is all about abandoning concepts of wins and losses, since these are absolute definitions, and in post-modernism you cannot have absolutes. Rather it becomes about caring for the emotions and personal journeys of the players, and that (said in the most obnoxiously trite voice ever) “they can be winners in life even if they lose. Since we’re all winners. Who are to judge them?”
That's why all this stuff is for non-fans, since it's a way to get everyone emotionally engaged in the players, though obviously all MLB cares about is that emotionally engaged = money. Which is another reason post-modernism is often so fake, because nobody actually cares about any of the above or lives those ideals, but I digress. Hell, I’d say when you look at the NHL standings and how messed up they are (i.e. teams aren’t ranked anymore by an absolute ordering of most points to fewest), that’s another example of post-modernism in sports.