Good question. I have hunted many BP over 4 months and I am convinced of certain things:
1) Yes Luck matters though i don't know fully how it factors in
2) Contents of footlockers is determined when map loads, not when container is opened
3) The Treasure Hunter perk is to be avoided now, until the next update. Players with TH are finding far less caps in containers than players without TH, which is backwards from intended
4) Lockpick skill 300 is extreme overkill and some guys say 150+picks is fine
5) Some lockers just don't open, no matter what
6) Even with LK 10 + AG 10 + PE 10, Lockpick 300 + lockpicks, some lockers open on 2nd (or 3rd) try
7) Sometimes it seems like BP act like resources as we go for 2 hours without a single find, while other times we find the exact same blueprint twice in a row within 10 minutes. This has happened too many times for it to be mere coincidence, giving rise to the "blueprint come in waves" theory.
Location on the world map doesn't seem to be a factor but do not take that from anyone - prove it for yourself
9) Trapped lockers don't seem to be any more consistently valuable than non-trapped lockers
10) There is no support group if you get addicted to hunting blueprints, nor a chewing gum to help you break the habit so be careful out there