Don't forget that Block Pass Pin can be used in any fighting situation, not just standing up. You can do it from Mount, Guard, side to side on the ground, arms vs. legs, legs vs. legs, etc. Be creative. The most challenging (i.e. fun) version I've experimented with was one person lying on their back and the other kneeling at the head, ala the "north/south" position in grappling.
Use the drill in any position you may end up in in a fight. One thing I do is have people free grapple, and on a signal, stop grappling and go into BPP from whatever position they are in at the time. You can also start sparring matches from this drill.
Joe