there was a discussion about this a while back, and it was clear to me that it doesn't make much sense. and it wasn't ever explained what it is based on anyway.
seems like it should just be an obvious, transparent formula that gives people a general metric of how involved a certain member is, and for how long. no. of years a member and/or registered, no. of reader reviews, no. of posts, gear list posted?, etc. and other things too? (i wouldn't include "no. of purchases from BPL" or anything like that.)
i'm not sure if it makes sense to differentiate between BPL member and registered "guest" user. seems like BPL thinks so, since your rank will drop a lot if you let your membership lapse.
it remains unclear to me why this isn't just explained to all in a transparent way. i was kinda opposed to including the BPL rank next to every user post, but if it makes sense and is explained clearly to all, i think it can have value, especially to newer users who aren't familiar with individual posters yet.
and hey jay, i have 2.5x as many posts as you, and my BPL Rank is only "1.18" - so don't feel bad... your rank blows mine out of the water! :)