Problem is the quality of the product.
ESPN has been horrible in terms of coverage of sports from a neutral standpoint. They try to go with the trends and hype up certain big market teams to create stories to sell their product, but this ends up alienating their fans.
They don't realize that this isn't a movie they are selling, it's an ongoing product that pretty much sells itself. It's not like Frozen where you root for one side, and then go sell products with their face plastered all over it to kids who are easily manipulated for a short period of time, you are selling the product (the entire sports) as a whole to people who are knowledgeable about that product, and is willing to continuously pay for insights and commentary.
Catering to big market teams alienated a lot of the smaller market team fans, and catering to casual fans is awful marketing because casual fans are not the type of people who are willing to pay money for something they will watch casually, anyways. I don't understand the political correctness of ESPN. I support being moral and upright, but do they seriously think that transgenders and their supporters will now be pay subscribers because Jenner got an award from them? Sports is a thing where you either like it or not, nobody ever watches sports because the network supports the causes they do.
Then there is the marketing of players, who in general has about a 5-year peak, if not less. You invest so much in a small number of players, and in many cases, alienated fans of the other top players due to rivalries that, once the small number of players you promoted are over the hill, and the players you ignored made it to the top, your network will now seem disingenuous for promoting these up and comers because you have been ignoring them for so long. Hardcore fans, which are fans who are willing to pay for insights and unique point of views, see through these things, and start going somewhere else.
And that is before talking about putting your bet on the wrong horse (Dwight in the early 10s, we will see how Durant recovers from the injuries, Curry is likely the next guy).