as a non-roster invitee who's still in major league camp, you're in the dugout and the bullpen for every game and available to play. for a player like bickford, it's a game-by-game basis to be invited. also, as mentioned earlier, minor league camp players are playing on fields further away from the main complex in the maryvale neighborhood of phoenix, and i believe in the case of the san francisco giants (whose facility is on a very small footprint in scottsdale with only one additional adjacent playing field), minor league camp is held at a different site. use google satellite view to take a look at cactus league facilities. the brewers are quite fortunate to have all of their playing fields on one mass of land. many other clubs have their adjacent playing fields for minor league camp separated by public roadways. at the complex in the maryvale, it's safe and convenient for fans and players to be able to freely walk back and forth without having to worry about vehicular traffic.