you should mention you mining which coin on which pool? did you use static diff or dynamic?
3978 accepted shares count by miner and proxy.
4137 is it accepted shares or only job that sent by miner? because I experienced with phoenixminer and ethermine pool, not all stale shares return by pool.
I think the way dev fee works is base on timer so I guess you cannot count dev fee base on accepted shares because every minutes accepted shares is different.
so if you want to prove somethings wrong with dev fee I think you should check when dev fee started and when dev fee ended.

for me I prefer to check statistic from pool side and try some of them (not only one).