If you had to pick just one thing that separates baseball fans from football and basketball and hockey fans, well, it might be this: Baseball fans love the game's rules. This is true for golf too, by the way. Golf fans love the rules. Golf fans can rhapsodize for hours about just Rule 13-1 -- "The ball must be played as it lies."
But this is even more true of baseball. Football, you probably know, changes its rules every other day. Now they're kicking from the 35-yard line. Now they're kicking from the 30. The goalpost many years ago was in the front of the end zone. That was silly, so they moved it to the back. One minute a quarterback in the grasp is sacked, the next minute a quarterback in the grasp is not sacked. A catch one year is an incomplete pass the next, and a catch the year after that. And don't even try to get into the differences between illegal contact, holding and pass interference -- it will make your head hurt, and by the time you figure it out, they will have changed it anyway.
That's not a knock. Football, basketball, hockey, the fans of these sports see their games as works in progress, not unlike the "more perfect union" words in the Constitution. If there's a problem, football fans and others want it fixed. If a player gets hurt with a horse-collar tackle, they want horse-collar tackles penalized. If punters take dives when rushers barely touch them, they want a rule for a five-yard running-into-the-kicker penalty rather than the 15-yard roughing call. They are proactive about their sports; they want them to fit the time.
Baseball fans, we don't like big changes. OK, let's just say it: We don't like any changes. The American League has been playing with a designated hitter for 45 years, and people still argue about it. Any rule change, even ones non-baseball fans would think of as minor or insignificant, will set off many baseball fans. We can spend hours fighting over the new rule to eliminate the four pitches thrown to intentionally walk batters. And, really, who should care about that?

We care. This is the challenge that Commissioner Rob Manfred faces as he tries to do what has to be done for future generations: Quicken the pace of play. There's something about baseball, something hard to define, that makes us treasure the rules. You will never see a basketball fan write poems about 15 feet being the perfect distance for a free throw. You will never hear a football fan sing songs of praise to the eight yards between the center and the holder on a field goal (it seems to me that, when I was a kid, it was only seven yards from center to holder).
But get one of us baseball fans talking about the perfection of 90 feet between bases or the poetry of 60 feet, 6 inches from rubber to plate or the gorgeousness of 162 games -- yeah, it can be a bit much. Other sports see their games as unfinished, raw; if something needs to be changed, then it should be changed. Why not?
Baseball somehow feels perfect to us true believers.
I really don't know why this is. It must have something to do with history; baseball is an older game than football, basketball and hockey. Baseball was not always like this. In the late 19th and early 20th centuries, they changed baseball rules like crazy. It took eight balls to walk someone, then six balls, then four. Walks were called hits and then they weren't. Pitchers had to throw underhand (which is why we still call them "pitchers"), and then they could throw overhand. Pitchers had to stay in a box, then they had to keep one foot on a slab, later called the rubber. The height of the mound was moved up and down. Spitballs were legal, then they were outlawed. There were a hundred such rule changes. It was a game in motion.
And then, as on "Seinfeld," there was no motion. From 1932-68, there were no significant changes made to baseball. It was as if everyone decided all at once: "Ah! It's perfect!" From 1969-73, mostly in response to a lack of scoring and dwindling fan interest, there was a brief flurry of changes -- lowering of the mound, adding the save, batting helmets became mandatory, the designated hitter was put in motion. Then nothing interesting changed in the rules for another 35 or so years, when replay was added and a couple of slide rules were changed for the players' safety.
More I think of it, the reluctance to change the rules in baseball isn't because of history, exactly, but instead because of continuity. Baseball fans, more than any fans of any other sport (again with the possible exception of golf), crave continuity. It's important to us that players today are playing fundamentally the same game that Babe Ruth and Satchel Paige and Willie Mays and Johnny Bench and Greg Maddux played.
When you talk to baseball fans about performance-enhancing drugs in the game, for instance, they are less likely to talk about the health hazards or how PEDs tilted competition and more likely to talk about Barry Bonds breaking Henry Aaron's home run record. It is the break in continuity that enraged so many. Forty home runs in a season, 500 home runs in a career, these things no longer meant what they had always meant. And that still sticks in the craw of so many.
With that, Manfred's adamant (and I think correct) desire to speed up baseball somewhat is met with what any other sports fan would see as surprising blowback. His interest in adding a pitcher's clock brings yelps from purists like me who love that baseball has always been the game with no clock. Manfred's interest in bringing the strike zone up brings fears that even a subtle change will hugely impact the game.
The NBA can tell its players "OK, fine, you can play zone now," and everyone is on board. Baseball tries to lift the strike zone a couple of millimeters and people panic that the game will lose any and all recognizable signs.
This is the delicate challenge Manfred and baseball face: changing the game without making it feel like change, keeping the continuity that captivates lifelong baseball fans while capturing new fans who are seeing the game for the first time. It isn't easy. But then, as Tom Hanks said, it's supposed to be hard. The hard is what makes baseball great.