Sherlock Holmes is a pitcher and John Watson is a catcher. No, no, no, it's a baseball AU.
Oh but John has such an excellent effect on Sherlock in this fic; it's a joy to watch Sherlock grow and John recover. If you're looking for a slowburn with a world and plot entirely its own, this is the fic for you.
Good - Sherlock is so very put out with the idiocy of his teammates, close to burning out entirely, and you can sense his interest in John Watson, an interest even he doesn't initially understand.