If they actually include the full list of encumbrance rules for 5e 8 str is going to be troublesome as soon as you hit 40lbs. Movement is reduced by 10 and then it starts to compound. We dont know currently if the system is just a WIP or fully implemented.
Also OP walking behind a mob doesnt give you advantage it gives you flanking rules. Flanking and Advantage stack.
Jaz
