re: How can you even make the case that college baseball is part of a "Big 3"?

Here is the deal

College Football and College Basketball differ from their pro counterparts - both sports produce a product that differs yet compliments its pro counter parts. For example we see a lot of diversity in offenses/defense schemes in college football compared to the NFL, and College Basketball is large and diverse enough to where it can be a lot of different things, while the NBA is a lot more run and gun.

College Baseball? What does it do differently than MLB that is a good thing? How does it differ?

IMO College Baseball is just an inferior product to MLB, it doesn't do anything better, while College Football/Basketball at least provide appealing alternatives to their pro counterparts.