"I didn't know you knew so much about baseball." I don't, but I was at someone's house with people who talked about scoring "points." It wasn't hard to seem like I knew something about it. I view it as "territorial" knowledge. Growing up as male in the 1970s I simply know the minimum that anybody in my situation would have to know. Like someone living in a town would know where the major streets in the town are.
You would know that if the catcher drops the third strike, he must throw to first.
That if the home team is ahead toward the end of the game, they can skip the bottom of the ninth. If they are behind in the bottom of the ninth, the minute the score, the game is over.
I knew that RISP is runners in scoring position (2nd or 3rd base). I know what era and rbi stand for.
I underestimated my baseball IQ because I am do not follow baseball very much, or watch it much except for when the local team is in the world series. I am not a baseball expert or serious fanatic at all. Yet I know that baseball has umps, not refs, the meaning of some basic terminology. I know you score runs, not "points."
We probably underestimate or overestimate our knowledge of many things. A speaker we had yesterday said that I new more about American poetry than most people in English departments would know. That is true.