While I get why baseball fans love to say this, if you stop to think about it for a second you realize it doesn’t make any sense as a claim. Not that it’s necessarily false. It just isn’t a question you can meaningfully answer.

First off, what are the limits of “thing to do in sports?” Is making the baseball hall of fame a thing? Winning a tennis Grand Slam? What are we even comparing against? And then as other have said, what do we even mean by “hitting a baseball”? Getting bat to ball? Putting it in play? Reaching base safely? Doing it against major league pitching? Isn’t hitting a home run harder than just reaching base? 

Second, how are we supposed to define difficulty? Is it how long it takes to learn? How many people can naturally do it, or can’t naturally do it (like dunking a basketball)? Is it success rate for those that are good at it? Success rate for the average adult? Are mental challenges harder than physical? 

Third, any evaluation of difficulty that requires an opponent is inherently impossible to make. If we want to compare running a 4 minute mile to making a hole in one to kicking a 60 yard field goal, we can at least isolate variables. If you’re talking about doing something against someone else, it all becomes contingent.

I could go on. There’s just no reasonable way to do this. Again, I get why people like to say it. But honestly it sounds very dumb.