Neither Southern Methodist University nor Boise State currently has an active intercollegiate baseball program.
So if they get invited to the Big 12, they'll be of absolutely no help to Big 12 Baseball.
The Big 12 doesn't need more schools that don't play baseball.
Conversely, the same sort of difficulties arise for potential Big 12 candidates that might have a good baseball program but have little else to offer the Big 12.
Rice, Wichita State, Creighton, Tulsa, and others might be able to pull their weight in Big 12 baseball, but none have a football program of the sort to earn a sniff from the Big 12 headhunters.
But stranger things have happened.