I found this recipe that explains about why baking powder is used in fried chicken batters.
http://everydaylife.globalpost.com/make-crispy-fried-chicken-baking-powder-31284.html
"From top chefs to Southern grandmothers, everyone has a different method and recipe for crispy fried chicken that they claim is the best. Some of these recipes advise you to add baking powder to the flour coating to give the fried chicken extra crunch. Baking powder creates very tiny air bubbles on the surface of the battered chicken when it is placed in hot oil. The bubbles expand the surface area of the batter, breaking up its thickness, which results in a lighter, crispier fried chicken."
Obviously this is for fried chicken but I don't see why it wouldn't have a similar reaction when cooking in a PBC/UDS/smoker,ect. I think once the fat starts to render out you would get the bubbles (explained above) which will crisp the skin.....just a theory though. Hopefully you'll figure it out for us....:mrgreen:
And don't let anyone discourage you with nonsense:thumb:. ...It happens here at times. ...:tsk: