Also, if baseball's not your game and you thought it was always boring, probably skip the rest of this post.
Now, I think both the application of analytics and the general development of human skills (100+ mph fastballs!) have necessitated tweaking the rules in some basic ways. I'm definitely not the first to note this -- MLB has a whole "competition committee" trying to make the games faster and better, so far without success AFAICT. I saw a postseason game this year that lasted 4 hours (for a 9-inning game).
The symptoms are well-known (long, boring games; batters either hit a homer or strike out or walk) and I don't need to list them all. But if you don't make the games faster and let the other 7 players on the defense get involved, nothing else is going to matter. Four hours when a game only took two just 60 years ago is not OK.
Rather than list all the possibilities, I'll just leave it at this: adult softball leagues have to finish the games in 90 minutes (for a 7-inning game). So how do they pull it off?
* The biggest rule change I can see adopting is foul balls. One foul after two strikes is all you get.
* They also start you at 1-1 count, but I think that one will never fly. There's something sacred about 3 strikes. Sorry.
MLB could make it 3 fouls, or 5, or some high number, and lower it over time. Who really enjoys watching a hitter foul off pitch after pitch? Hitters can pretty much do it all they want nowadays, which is what I meant by "the development of human skills." Eventually, if it's a strike you have to swing at it.
Besides wasting huge amounts of time, it makes for way too many pitching changes. MLB's already tried tweaks to reduce those, but they've had pretty much no effect.
Being conservative about the rules was fine for the last 150 years, but I really think those times are over.