Being bronze is harsh especially when u win rarely and the electricity goes off when u are wining
Why would winston work? Not enough burst and you can't do anything from long range.
d.va is just so good, you can finish off low targets far away, you can micro missile targets down, you have a good team wipe ult and you can get a new life against bronze ppl who probably have trouble killing baby dvas.
I used to coach a bronze-gold team for a short time, and what i learned was play: winston, torb and hog (and moira if you have to heal) they're wildy op on those lower ranks (especially hog if you have decent aim), yes even more op than brig (many low rank people lack the positioning/"intelligent" aggression Brig requires...ye i know...)