well first you know that the BPHR is located on teh card by the # symbol right?
So then W power hitters will NEVER have any, because they have no power. They may have some natural HR power, but no BPHR rolls.
Tha BPHR roll, wether off the hitters or pitchers card is the same, it uses the parks HR rating to see if it is a HR of a Fly(B). The rating is of course a roll of 1-20, it if is = or under the BP rating for HR for the park, is is a HR. So for Shea, it is good for a LH hitter to ht a HR, but not a RH hitter.