I made the mistake of listening to Colin Cowherd a few weeks ago. The exact circumstances are irrelevant, but let's just say I forget his show starts at 9am, right after Mike & Mike. I don't think Cowherd needs much introduction for sports fans, but in case you're one of the smart ones to never listen to sports radio, he's an ESPN talking head that might hated more than he's loved. Bombastic, nasally, all the things you'd probably sketch out if you were making a parody of a drive-time radio host.
To be fair to Cowherd, he's not all bad. He understands media, and football. The unfortunate thing is nearly any topic he covers is put into these frameworks. Talking about baseball? Let's talk about TV ratings for 30 minutes! Do people like good pitching? No! They like touchdowns!
The specific segment I heard was something about how modern American sports fans prefer the big offense, and although that's true to a certain degree, I don't think it's as deterministic as he'd like to believe.
Chicks dig the long ball, or so Nike convinced us in the Steroid Era. The home run races in the late Nineties were considered a major factor in repairing baseball's post-strike popularity. Home run derbies became a marquee event (compare with the 1990 event, which had Ryne Sandburg win with only 3 home runs), and home runs became the signature highlight on Sportscenter. It'd seem people really love high offense, right?
Of course, if we assume that the existence of more home runs in the 90's contributed to a resurgence for the game, we'd also expect that the decline of home runs in the latter part of the 00's until would also cause a decline in interest of the game. Yet that argument wouldn't be completely salient. Any decline in attendance in the past 5 years is more local and recession caused than a grand narrative related to home run power. So it would seem that home runs were only an extraneous variable, but not the true independent variable. It's more likely that any rise in baseball popularity coincided with the tremendous economic boom America saw in the 90's.
Cowherd would tell you (as he has seemingly every time I have the displeasure of listening to his show) that you can see popularity through TV ratings. I think that's only part of the puzzle, however. It would be foolish to compare the Super Bowl, an singular event on a weekend, to the World Series, a series of events held on both weekdays and weekends. It would be foolish to assume that all baseball fans want to watch the World Series after a long season if their team isn't in it, whereas the Super Bowl is often the only reason to watch gridiron football for non-fans and fans of bad teams. Baseball's interest is fractured into its individual team-nations, not consolidated into the central governing body.
Perhaps most damning to the argument that fans prefer offense is that we can't separate out that behavior simply from the sum of the actions. In other words, it's impossible to assume that since people watch a game, which is the result of many motivations and desires, that therefore people must watch because of one variable. It's too easy to think of other conditions that might affect viewership to single out offense. The only way to reasonably make the argument would be to survey fans, but to also determine if a lack of offense, or home runs, would be enough to deter further viewership.
The fact of the matter is that fan attention will peak and fall like ocean waves due to a variety of factors. But a fan of the game, or especially a team, has one true motivating factor and that's the game, or team, itself. A fan of the Diamondbacks likely won't stop watching because the HR/9 is down for the team.