considering that Baseball isn't usually played in an Arena...not sure
"Bball" is common urban vernacular for basketball that has even crossed over to mainstream outlets like ESPN. If you Google "bball", every result on the first page is basketball related. OTOH, anecdotally, I've never heard anyone refer to baseball as "bball".
EDIT: Also "men's bball" is particularly clear since the NCAA does not have women's baseball teams.