actually, in minor league camp they alllll have their last names on the back of their jerseys. I don't have a picture, but we get to Spring Training most years, and those jerseys have names...it's just when they go play in a MLB game, they get a different jersey with a different number. It's also not unusual for there to be several folks with the same number playing in the same group, so can't just yell "hey 8, get a move on". Coaches generally seem to use last name, and especially at the beginning of ST, there are a lot of guys around, so I'd think the names on the back would be a sanity saving measure for the coaching staff, if nothing else :D