It's really kind of simple, OBP has a higher correlation to team overall scoring than BA does. Think of it in terms of evaluating chicks. BA would be like only knowing the size of her breasts. OBP would be like knowing the size of her chest and the shape of her rump. OPS would be like tits, ass, and face. VORP would be like tits, ass, face, and demeanor. Linear Weights would be like tits, ass, face, demeanor, and what her mother looks like (a good approximation of what she'll look like in 25 years).
Now, with BA, she could be a real winner, but fat chicks have big hooters too, so it doesn't tell you as much as the others. With OBP, you'd at least know if the nice rack was on well proportioned body.
Does this help?